OKLAHOMA CITY - Police are looking for a serial robber who pistol-whipped a motel clerk Wednesday night in southwest Oklahoma City.

About 11:30 p.m., police were called to a motel at 400 S Meridian Avenue. A motel clerk told police he was hit by a man who was robbing the cash register. 

The clerk, who suffered several cuts and bruises on the top and side of his head, said a man pointed a black handgun at him and demanded for all the money.

The clerk told police he tried to stop the robber from getting to the cash register but that's when the man hit with weapon. Police later determined the weapon was BB gun, according to the incident report.

Police think the man also robbed four other motels; a motel near Reno and Meridian avenues on Oct. 6, a motel near Interstate 35 and S Grand Boulevard on Oct. 8, and a southwest motel and a Midwest City motel on Oct. 9. 

"We're obviously concerned that he's escalating in the way that he's committing these robberies and want to get him off the streets before he can strike again," the police department said on their Facebook.

The man is described as being a large black man, about 6 feet 1 inches to 6 feet 4 inches tall and weighing about 250 to 300 pounds. He reportedly got into a black, four-door sedan but police could not determine the make or model of the vehicle.

Police say they know the man isn't acting alone. Video surveillance captured what appears to be a getaway driver. There were two vehicles used in the commission of these robberies. A black four door sedan, and a silver van with a handicap placard on the back window.

Anyone with information is asked to call Crime Stoppers at 405-235-7300 or submit a tip online at www.okccrimetips.com. This is case number 18-81994. Tipsters may remain anonymous and may be eligible for a cash reward.