Three Chicago Police officers were injured, one of them seriously, in a crash between a van and an unmarked police car Wednesday morning in the South Side Gresham neighborhood.

The officers were on their way to reports of a robbery in progress at 10:18 a.m. in in the 200 block of West 87th when their unmarked squad car pulled up behind a van about to cross the intersection the 8300 block of South Halsted, according to Chicago Police.

The officer driving the unmarked squad car attempted to pass the van on the left when the van tried to make a left turn, hitting the squad car and causing the squad car to hit a light pole, police said.

Police said the unmarked car was using its emergency equipment at the time of the crash.

All three police officers were taken to Christ Medical Center in Oak Lawn, police said. The driver was listed in serious condition while the other two officers’ conditions were stabilized.

The driver of the van was not hurt, police said.

Further details were not immediately available.