RCMP have provided new details around the timeline of a manhunt for a gunman who killed 22 people in Nova Scotia over the weekend.

Police have also said that they have a "fairly good idea" that the gunman did not have a firearms licence in Canada.

On Wednesday, RCMP Chief Supt. Chris Leather said police first responded to a possible shooting at 10:26 p.m. AT on Saturday in the rural community of Portapique, N.S.

Leather said that it was determined to be a homicide, and police began searching the area. But the only information provided to the public at the time was a tweet at 11:32 p.m. AT saying they were responding to a firearms complaint and asking residents to lock their doors.

Leather said officers set up a perimeter and continued their search for the suspect throughout the night.

Following new information that the suspect was not in the secure perimeter, at 8:02 a.m. AT on Sunday, RCMP began providing more real-time information on Twitter.

Police working on an alert when gunman was killed

The police force has been criticized for not putting out a provincial alert at any point over the weekend.

Leather addressed that on Wednesday, saying at 10:15 a.m. AT Sunday provincial emergency management officials reached out to offer use of the alerting system.

Leather said there were delays in communications between the province and various officers, as well as the discussion about what the message would say.

"We were in the process of preparing an alert when the gunman was shot and killed by the RCMP," Leather said.

Leather said it was between 7 and 8 a.m. AT Sunday that police received information the shooter was dressed as an RCMP officer and driving a vehicle made to look like a police cruiser. He said this was after a key witness was located and interviewed.

Leather said as soon as police had those details, they were immediately tweeted out by communications staff. The tweet was sent at 10:21 a.m. AT.

Police said they cannot identify the firearms used by the suspect at the time he was stopped by police, as that information is with the Serious Incident Response Team, the province's police watchdog.

Leather said where the gunman got his firearms is "a key part of the investigation."

Leather said he is hopeful that a timeline with more details can be shared within a day or so.

"We are still piecing together the movements of this subject. We believe we have identified the locations and sites and when he did [what], but there certainly are gaps," he said.

Leather said one person was injured during the rampage. They sought medical attention and have since been released. Leather said he is not aware of any others who were injured and are recovering in hospital.

WATCH | Video shows gunman wearing uniform, changing clothes

Surveillance video obtained by CBC News shows the suspect in the Nova Scotia shootings briefly pulling into a parking lot and changing clothes. 0:59

Leather confirmed on Wednesday that the gunman acted alone, but said police are continuing to investigate whether anyone assisted him leading up to the shooting.

Police have set up a tip line looking for information about events leading up to the mass shooting.

"If you know something, please call," Leather said. "Let our investigators decide the value of the information, because that piece of information you have may be an important part of the puzzle."

The tip line is 902-720-5959.

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