Four people, including two children, are missing after the land beneath their home gave way and swallowed their house northeast of Montreal, officials said today.

Rescue authorities said the house partially collapsed overnight in Saint-Jude, a town of 1,000 near the Yamaska River, when a sinkhole formed.

"It's a pretty gigantic crater," said Francois Gregoire, a Quebec fire department spokesman. "It's hard imagining something like this. It's pretty impressive."

Gregoire said the house was quite far from the river before the land gave way but that part of it ended up in the water.

He said three cars in front of the house were swept away, as was part of a nearby road.

Sinkholes can occur when water undermines an area of land or when rock below the land surface shift.

Gregoire said rescuers were able to get to the collapsed house, but could not locate the missing man and a woman in their 40s and their children, aged about 9 and 11.

Quebec provincial police spokesman Ronald McInnis said firefighters got into the house but had to retreat when it started moving again.

"Then other firefighters from St-Hyacinthe came, got into the house and the same thing happened, so they also got out," he said.

Soil scientists later arrived on the scene to determine if the ground was stable enough for rescuers to re-enter the home, he said.

Mayor Yves Bellefeuille said the community is in shock, especially since the home is not in an area considered to be at risk.

Police said at least five other houses have been evacuated in the area, affecting about 20 people. Police have closed a stretch of a secondary road where the houses are located.

- AP