A 53-year-old man killed in a motorcycle crash Saturday afternoon on Tucson's west side has been identified. 

Michael Bell and a friend, were riding their motorcycles westbound on West Bopp Road near South Kinney Road when another motorcyclist traveling behind the pair crashed into Bell's motorcycle, causing him to lose control, Deputy Tracy Suitt, a Pima County Sheriff's Department spokesman said in a news release. 

The 59-year-old driver of the motorcycle that struck Bell was speeding and passing cars in a no passing zone before the crash, the release said. 

Both men were taken to the hospital, where Bell was pronounced dead. 

The other man is in serious condition. 

Neither man was wearing a helmet, the release said. 

Deputies believe speed and alcohol may have been factors in the crash. 

The person who was riding with Bell did not stop after the crash and deputies ask anybody with information about him or the incident to call 911 or 88-CRIME (882-7463).