C-Train passengers at the Sunnyside station wait for a shuttle bus to take them downtown Thursday morning. (CBC)

A man was taken to hospital in life-threatening condition early Thursday after he was found on the LRT tracks in downtown Calgary suffering from a severed leg.

He was discovered at about 3:40 a.m. near Centre Street and Seventh Avenue, police said.

Early indications are that the man in his forties fell from the station platform and became lodged between two moving train cars, said Insp. Keith Cain.

The man's leg was severed below his knee and he suffered serious head injuries, Cain said.

Police said he wasn't pushed, and are still trying to find out if he was intoxicated or distracted by something like an iPod.

Insp. Dave Wood said it could have even been worse, if not for the actions of a group of Calgary Transit rail maintenance workers who were working nearby at the time.

"It was great work by the city worker that did find him on the side and alerted police and EMS," Wood said.

C-Train service into the downtown area and to northwest Calgary was disrupted for several hours while police investigated the incident.

"So we did have shuttle buses in place," said Calgary Transit spokesman Ron Collins.

"[In] the northeast ... the trains would go as far as Bridgeland station and then shuttle buses from there. From the south as far as Stampede station — shuttle buses from there. And once we were able to get trains up into the northwest, we had train service from Somerset to the Sunnyside station and then shuttle buses from that location."

Service was restored by about 7:45 a.m., city officials said.