CHICAGO (CBS) — A new group of mounted Chicago police officers has hit the streets, after completing what they said was some of the most difficult training of their lives.

The officers ran their equine partners through a demonstration that included a police SUV barreling into the training arena at the South Shore Cultural Center.

The horses stood perfectly still as the SUV circled them, tires spinning, horn and sirens blaring, and a capgun blazing – all noises the horses might encounter on the job.

“The accomplishment, the unit itself is very prestigious. I’m just glad to be here and get through it,” Sgt. Glenn Lopez said.

Officer Jennifer Collins said the training was extremely difficult, physically and mentally.

“I love horses. I’ve always wanted to have a horse, ride a horse. This is my dream job, so absolutely very thrilled right now,” she said.

The class started with 15, but just four officers made it to graduation to join the mounted unit.