Police say the efforts of a suspect looking to dump a gun after a multi-vehicle crash on Deerfoot Trail Friday were foiled by a witness.

Police say they tried to pull over a Chrysler 300 around 8:40 a.m. MT at Deerfoot Trail and 32 Avenue N.E. for a traffic infraction, but the driver sped away and officers did not chase him.

A short time later, they received reports of a vehicle speeding on the shoulder of southbound Deerfoot Trail.

The vehicle entered the westbound 16 Avenue turnoff where it collided with the back of a minivan carrying a mother and her children — an 11-year-old boy and eight-year-old girl — who were taken to hospital with minor injuries.

Two men in a pickup truck were also taken to hospital, said EMS.

Several witnesses stopped to help and as one of them approached the suspect, he saw the man grab a handgun and throw it into the ditch before running from the scene.

The witness went into the ditch to retrieve the gun and put it in his trunk before tending to the injured family.

Police say the suspect then returned, opened the trunk door and took the gun. He then ran into the nearby ravine and was witnessed throwing the gun into the creek.

It's believed the witness and at least one other person followed the suspect and were able to subdue him until police arrived.

The Calgary Fire Department Aquatics Team found the gun in the creek and has sent it off for testing. The suspect has been taken into custody and charges are pending.