LAHORE, Pakistan (AP) — India fired attack drones into Pakistan on Thursday, killing at least two civilians, the Pakistani military said. India, meanwhile, accused its neighbor of attempting its own attack, as tensions soared between the nuclear-armed rivals.

India acknowledged that it targeted Pakistan’s air defense system, and Islamabad said it shot down several of the drones. India said it “neutralized” Pakistan’s attempts to hit military targets. It was not possible to verify all of the claims.

The exchanges came a day after Indian missiles struck several locations in Pakistan, killing 31 civilians, according to Pakistani officials. New Delhi said it was retaliating after gunmen killed more than two dozen people, mostly Hindu tourists, in India-controlled Kashmir last month. India accused Pakistan of being behind the assault. Islamabad denies that.

Both sides have also traded heavy fire across their frontier in disputed Kashmir, and Pakistan claimed it killed scores of Indian soldiers. There was no confirmation from India.

Late Thursday, in Indian-controlled Kashmir, residents of the city of Jammu reported explosions and sirens, followed by a blackout.

India’s Headquarters of the Integrated Defence Staff, a central coordinating arm for all Indian armed forces, said military stations in Jammu, Udhampur and Pathankot were targeted by Pakistan using missiles and drones. It said the attacks were repelled and no casualties were reported.

Shesh Paul Vaid, the region’s former director-general of police, told The Associated Press that the Jammu Airport likely was also under attack and that some of the 50 loud explosions he heard likely were because “our defense system is at work.”

Jammu and Udhampur are close to the Line of Control, the de facto border that divides the Kashmir region between India and Pakistan. Pathankot is in India’s Punjab state.

Sirens were also heard in some parts of the region’s main city of Srinagar, residents said. It was followed by a blackout in the city and other parts of the region.

Pakistan’s Ministry of Foreign Affairs in a statement rejected the Indian claims that Pakistan launched attacks on Pathankot, Jaisalmer and Srinagar, saying “these claims are entirely unfounded, politically motivated, and part of a reckless propaganda campaign aimed at maligning Pakistan”.

It added that “such actions not only further endanger regional peace but also reveal a disturbing willingness to exploit misinformation for political and military ends”.

Pakistan’s Prime Minister Shehbaz Sharif has vowed to avenge the deaths in India’s missile strikes, raising fears that the two countries could be headed toward another all-out conflict. Leaders from both nations face mounting public pressure to show strength and seek revenge, and the heated rhetoric and competing claims could be a response to that pressure.

U.S. Secretary of State Marco Rubio spoke Thursday to the Pakistani prime minister and India’s External Affairs Minister Subrahmanyam Jaishankar, urging both sides to de-escalate the situation, the U.S. State Department said.

The relationship between countries has been shaped by conflict and mutual suspicion, most notably in their dispute over Kashmir. They have fought two of their three wars over the Himalayan region, which is split between them and claimed by both in its entirety.

With tensions high, India evacuated thousands of people from villages near the highly militarized frontier in the region. Tens of thousands of people slept in shelters overnight, officials and residents said Thursday.

About 2,000 villagers also fled their homes in Pakistani-administered Kashmir.

Mohammad Iftikhar boarded a vehicle with his family on Thursday as heavy rain lashed the region. “I am helplessly leaving my home for the safety of my children and wife,” he said.

India fired several Israeli-made Harop drones at Pakistan overnight and into Thursday afternoon, according to Pakistani army spokesman Lt. Gen. Ahmad Sharif, who said 29 were shot down. Two civilians were killed and another wounded when debris from a downed drone fell in Sindh province.

One drone damaged a military site near the city of Lahore and wounded four soldiers, and another fell in the garrison city of Rawalpindi, near the capital, according to Sharif. “The armed forces are neutralizing them as we speak,” he told state-run Pakistan Television.

In Lahore, local police official Mohammad Rizwan said a drone was downed near Walton Airport, an airfield in a residential area about 25 kilometers (16 miles) from the border with India that also contains military installations.

India’s Defense Ministry said its armed forces “targeted air defense radars and systems” in several places in Pakistan, including Lahore.

New Delhi, meanwhile, accused Pakistan of attempting “to engage a number of military targets” with missiles and drones along the Line of Control that divides Kashmir and elsewhere along their border. “The debris of these attacks is now being recovered from a number of locations,” it said.

At a news briefing, Pakistan’s Foreign Minister Ishaq Dar on Thursday rejected India’s claim that Islamabad carried out any attack in Indian Punjab. “These accusations are an attempt to incite anti-Pakistan sentiment among the Punjabi Sikh population in India,” he said.

Seated alongside Dar, the military spokesperson, Sharif said Pakistan shot down 29 Indian drones after they violated its airspace.

Pakistani Information Minister Attaullah Tarar told parliament that so far Pakistan has not responded to India’s missiles attacks, but there will be one. Later Thursday, Indian authorities ordered a night-time blackout in Punjab’s Gurdaspur district, which borders Pakistan.

The Harop drone, produced by Israel’s IAI, is one of several in India’s inventory, according to the International Institute for Strategic Studies’ Military Balance report.

According to IAI, the Harop combines the capabilities of a drone and a missile and can operate at long ranges.

The two sides have also exchanged heavy fire over the past day.

Tarar said that the country’s armed forces have killed 40 to 50 Indian soldiers in the exchanges along the Line of Control. India has not commented on that claim. Earlier, the army said one Indian soldier was killed by shelling Wednesday.

Tarar denied Indian accusations that Pakistan had fired missiles toward the Indian city of Amritsar, saying in fact an Indian drone fell in the city. Neither claim could be confirmed.

India’s Foreign Ministry has said that 16 civilians were killed Wednesday during exchanges of fire across the de facto border.

Pakistani officials said six people have been killed near the highly militarized frontier in exchanges of fire over the past day.

Indian Foreign Secretary Vikram Misri denied that New Delhi has targeted civilians and a key dam, as Pakistan has alleged. He, in turn, accused Pakistani forces of targeting civilians, including at a Sikh Temple in Kashmir, where he said three Sikhs were killed.

Flights remained suspended at over two dozen airports across northern and western regions in India, according to travel advisories by multiple airlines. Pakistan resumed flights nationwide after a suspension at four airports, according to the Civil Aviation Authority.

Ahmed reported from Islamabad; Saaliq reported from New Delhi and Hussain reported from Srinagar, India. Associated Press writers Rajesh Roy in New Delhi, and Ishfaq Hussain and Roshan Mughal in Muzaffarabad, Pakistan, contributed to this report.