DENVER -- A 9-year-old girl remains in critical condition Monday morning after being hit by a Jet Ski.

The girl was being towed in an inner tube behind a boat on the west side of Chatfield Reservoir Sunday when a red personal watercraft hit her. This occurred about 5:30 p.m.

She is was airlifted to Children's Hospital and is in critical condition with severe head and internal injuries. Her name has not been released.

According to Chatfield State Park authorities, two teenage girls were operating the Jet Ski.

Authorities said that the girls were going north along the Massey draw shoreline when they passed close to the boat and made a 90-degree turn toward the shore.

Their watercraft knocked the 9-year-old girl in to the water. Another 10-year-old girl also being pulled in the tube was uninjured.

The two teenagers, who were wearing black life vests, were thrown off but got back on their jet ski and took off.

A man driving nearby a blue jet ski helped the injured girl get back on the boat, operated by Gary Barkley.

Police consider the accident a hit-and-run and are looking for the teenagers.

If you have information, you are asked to contact Colorado State Patrol dispatch at (303) 239-4501.