A woman was shot and killed by police Wednesday in Calgary when officers responded to a welfare check.

Police were called to a home in the southeastern Legacy neighbourhood just before 1:30 a.m. for a mental health call from a woman.

Chief Katie McLellan said officers had encountered the woman several times in recent months.

About an hour later, police said the woman came out of the house with a weapon. Police have not said what the weapon was.

The situation then escalated, police said, and an officer shot and killed the woman.

“What occurred this morning is just one incident in a string of concerning events where officers have been confronted with violence, weapons and rapidly escalating threats while responding to calls around Calgary,” McLellan said at a news conference.

“This is a significant concern.”

During the encounter, a gas meter ruptured, causing a leak.

Fire crews shut off the gas line and nearby homes were evacuated, police said, but residents were able to return soon after.

One officer was taken to hospital as a precaution, while another was assessed by a medic on scene.

The Alberta Serious Incident Response Team is investigating, as is standard practice for police-involved shootings.

McLellan said encounters that begin as routine can change in seconds and more often than ever before, firearms are part of the new reality.

About eight times a day police encounter situations involving firearms, she said, and there are about 40 calls a month about an officer in trouble.

“This has become a new normal and it has consequences for our officers, their families, our service and the community that we are here to protect,” she said.

“Officer-involved shootings are among the most difficult moments we face as a service.”

McLellan said there’s constant anxiety about the safety of her officers. “It’s what keeps me up at night.”