Police say a suspected hit-and-run driver who is believed to have intentionally mowed down a pedestrian in northeast Calgary is dead after being Tasered by police, and the pedestrian is in hospital with life-threatening injuries.

A witness called 911 to say they thought a driver had "intentionally hit" a pedestrian, according to Acting Deputy Chief Ryan Ayliffe of the Calgary Police Service.

"We believe this is a targeted incident," the officer told reporters.

The pedestrian was struck at McKnight Boulevard and 52nd Street N.E. at about 3:40 a.m. The man, believed to be in his mid-40s, was taken to Foothills Medical Centre, where he remains with life-threatening injuries.

The suspect, who is believed to have known the pedestrian, died in police custody after being Tasered, Ayliffe said.

The deputy chief held a news conference Wednesday afternoon to offer more information, though details were limited.

As is standard procedure with a death in custody, the Alberta Serious Incident Response team (ASIRT) is now investigating.

Six officers — five from patrol and one from the canine team — are being interviewed by ASIRT. They will all be put on 30-day administrative leaves for their health, Ayliffe said.

The Alberta Serious Incident Response team (ASIRT) is investigating after a hit and run on McKnight Boulevard ended with the suspect dying in police custody. (Mike Symington/CBC)

A short time after police arrived to investigate the pedestrian being hit, officers found the suspect's vehicle at 68th Street and 32nd Avenue N.E.

There was a struggle as officers tried to arrest the man, police said.

The man refused to leave his vehicle, Ayliffe said, so a Taser was used on him. A K-9 unit was deployed, as well.

Once he was in custody, the driver appeared to go into medical distress. He was taken to hospital, where he was pronounced dead.

The cause of death has yet to be determined, Ayliffe said. It could take several weeks to a month before that is confirmed.

Ayliffe said the man was in his late 40s and was known to police.

Kim Kuntz, who lives nearby, stopped by the scene before taking an alternative route. She said it was "crazy" to see so many police officers in the area.

Kim Kuntz, who lives nearby, says she was surprised to see so many police in her neighbourhood Wednesday morning. (Mike Symington/CBC)

"They're supposed to keep us safe. So if that was a suspected hit-and-run, then they need to investigate. If the guy ran or whatever — they're saying … he was in medical distress, so I hope that was the case."

The roads around the scene were closed for hours.

Ayliffe offered words of support to the six officers involved.

"They are on our streets day and night ... (and) face complex, dynamic situations in which high stakes decisions must be made in split seconds," he said.

The officers are being placed on a 30-day administrative leave.

"That is strictly to look after their health and wellness. It allows us to make sure we avail every resource possible to them and their families so they feel as though they're in a good position to resume duties or explore further treatment."