SARNIA, Ontario (AP) _ Part of a shopping mall roof collapsed Thursday after more than 20 inches of snow fell, killing one shop worker and injuring another, police said.

The Lambton Mall was closed when the flat roof over a card shop caved in before doors opened, police officer George Linton said.

One woman, 47, died after being pulled from the debris an hour after the roof collapsed, the Canadian Press reported. Another worker was treated at a hospital and released, it said.

Janet Holiday, a mall employee, said she heard ``this horrendous big noise'' and snow, metal girders and water pipes filled the card shop.

Sarnia, a city at the southern end of Lake Huron about 180 miles southwest of Toronto, received heavy snow on Monday and a second layer Wednesday night.

Sarnia Mayor Mike Bradley said engineers were examining the rest of the mall for dangers of a further collapse.

``This is a wake-up call to other communities to start removing their snow quickly,'' he said.