RCMP responded to an explosion that killed a woman in Innisfail. Tara Weber/CBC

Police are investigating after a 23-year-old mother was killed Friday in an explosion at a townhouse in Innisfail, Alta.

The death of Vicky Shachtay, who used a wheelchair, is being investigated as a homicide, police said.

Her six-year-old daughter is now with family.

The woman's caregiver — a woman in her 30s — suffered minor injuries.

A package was delivered to the residence shortly before the explosion, RCMP said. It was left at the door, rather than delivered by a courier or postal worker.

The incident happened around 9 a.m. at a fourplex near downtown Innisfail, which is about an hour north of Calgary.

Three other units were evacuated, but damage was confined to the one unit.

The cause of the blast is not yet clear. The major crimes unit and explosive experts were called to the scene of the blast, Sgt. Patrick Webb said.

Officials are advising people to be cautious about any unexpected packages that are delivered.