MOORESBORO (AP) — A North Carolina State Highway Patrol trooper and a South Carolina man he was detaining were killed Monday night when the trooper’s brother, also a trooper, hit a stopped patrol vehicle as he arrived to help with a traffic stop, officials said.

The crash happened around 9 p.m. during a traffic stop in the Mooresboro area, the Highway Patrol said in a news release.

Trooper James Horton was responding to help his brother, Trooper John Horton, with a traffic stop when he lost control and hit the stopped patrol vehicle, which in turn struck Trooper John Horton and the detained driver on the roadside, officials said.

Trooper John Horton, a 15-year veteran, was taken to a hospital, where he died, officials said. The detained driver, identified as Dusty Luke Beck, 26, of South Carolina, was pronounced dead at the scene. Trooper James Horton was treated at a hospital and released.

It’s not yet known whether the crash was weather-related, patrol spokesperson First Sgt. Christopher Knox said in an email.

“For all involved in this tragic event the coming days will undoubtedly be difficult, but we are committed to stand alongside with them with our thoughts, prayers and unwavering support,” patrol Commander Col. Freddy Johnson Jr. said in a statement.