Tucson police are attempting to identify a man who beat up a Circle K clerk on Tucson's south side Monday.

The clerk, who was working at the convenience store at 2 W. Valencia Road, was punched, kicked and slammed on the floor head first by a man in the store at about 10 p.m., according to a Tucson Police Department Facebook post. The Circle K is near South Sixth Avenue.

The clerk was taken to a hospital and is in critical but stable condition, police said.

After viewing surveillance video, detectives said it appears the clerk and assailant know each other.

Police said the assailant entered the store and began arguing with the clerk. During the argument, the man punched the clerk over the counter, and then walked around the counter and continued to beat him, causing a serious head injury. The clerk was punched and kicked in the head multiple times by the man before he left the store.

Police said the man is described as Hispanic and is about 35 to 40 years old. He is 5 feet 8 inches tall and weighs about 225 pounds. He has a tattoo of a cross on his right forearm.

Anyone with information is asked to call 88-CRIME, an anonymous tipster hotline. 

Contact reporter Carmen Duarte at cduarte@tucson.com or 573-4104. On Twitter: @cduartestar