Police are investigating after a woman was found dead on a CTrain at Whitehorn station on Sunday morning.

The station is completely closed as police work to determine if the woman’s death is considered suspicious.

“At this stage, we can’t determine if these are natural causes or suspicious circumstances,” said Det. Matt Baker.

Please note that Whitehorn LRT station is closed due to a police investigation. Currently no public access allowed. @calgarytransit #yyc — Calgary Police (@CalgaryPolice) March 2, 2014

Two LRT security staff who were patrolling the station found the woman slumped over in her seat on the CTrain just before 11 a.m. Sunday, said Baker.

When they approached the woman, the security staff realized she was in medical distress, and promptly called EMS.

EMS spokesman Adam Loria said EMS received a call for an unresponsive individual on the CTrain just before 11 a.m. Sunday.

When crews arrived at the Whitehorn LRT station, the person had no vital signs and was pronounced dead.

Investigators are pouring over CCTV footage and speaking to witnesses as they work to determine where the woman got on the train and who she was with.

Baker said it appears the woman may have been with two men, although police are unsure if the men were known to her or just sitting near her.

Police located one of the men on a southbound train and are still looking for the other.

At this point, the men are both considered witnesses, Baker said.

Whitehorn station has been closed as police investigate. No public access is allowed at the station.

Whitehorn station shuttle can be caught on NB/SB 36st. Look for Orange Emergency signs as to where to pick up. — Calgary Transit (@calgarytransit) March 2, 2014

More to come ...