A family's pit bull was shot and killed by police in a Riverdale yard last night after officers from three jurisdictions chased an assault suspect through Prince George's County, Bladensburg police said.

The incident began with an attempted traffic stop by a Bladensburg officer about 6 p.m. in the 4600 block of Annapolis Road. Bladensburg police said the driver hit the officer with his Dodge Durango and sped away. Other officers pursued the driver into the 5700 block of Nicholson Street in Riverdale Park, where the man got out of the vehicle and fled, police said.

A Prince George's canine unit was called in, and, during the search, a pit bull attacked the police dog in the 6000 block of Madison Street, authorities said.

The Bladensburg officer was treated at a hospital and released. The county police dog suffered injuries to two legs, including a hairline fracture and a laceration, county police said.

The family of the pit bull said that Pee Wee, their pet of nine years, was inside their gated back yard when it got into a scuffle with the police dog. A Riverdale Park officer shot the pit bull, said Wanda Brunson, the sister of the dog's owner.

Riverdale Park police did not return phone calls. Bladensburg police are searching for the Durango driver.