Two service members were killed and another is in serious condition following a vehicle accident earlier Tuesday in Santa Teresa, New Mexico, the United States Northern Command (NORTHCOM) said in a statement.

Shortly before 9 a.m. “Three service members deployed in support of Joint Task Force Southern Border were involved in a vehicle accident,” NORTHCOM said.

Tuesday’s accident are the first fatalities associated with the United States military’s mission along the border with Mexico that have been disclosed.

More than 10,000 active duty service members have been authorized for the border mission.

The cause of the accident is under investigation, officials said.

This is a developing story. Please check back for updates.