A Sacramento Regional Transit light-rail train got derailed after colliding with a maintenance train Thursday night, injuring 27 people on board. Nearly 15 ambulances reached the spot for assistance and transported 13 people to nearby hospitals.

According to Sacramento Regional Transit (RT), a test train and a two-car passenger train collided on the blue line tracks near Roseville Road. It’s unclear at this time how the collision occurred, CBS Sacramento reported.

RT informed that 3 employees were on the test train and none got hurt.

The officials are investigating the cause of the crash and are planning to clear the trains by the morning.

It is the second collision to occur between two trains in Sacramento since RT began operating light-rail service in 1987, according to The Sacramento Bee.

train collision At least two people have been killed after a train derailed close to Milan, Italy, Jan.25, 2018. Rescuers work after a head-on collision between two trains, near Corato, in the southern Italian region of Puglia, July 12, 2016. Photo: Getty Images