THE HAGUE, Netherlands (AFP) - About 20 people were injured in the western Dutch town of Alphen aan den Rijn on Monday when two cranes working on a bridge upgrade toppled onto houses nearby, the fire brigade said.

"Two cranes and the stretch of roadway they were carrying fell on five houses in all," Mr Ton Koot, brigade spokesman for firefighters of the central Holland region, told AFP.

"There are about 20 injured," he said, giving preliminary figures from first responders, who were being aided by air-ambulance helicopters.

The cranes, working from barges, were renovating the Queen Juliana Bridge, a canal bridge dating from the 1950s, when the first machine went down.

Unbalanced by the extra load, the second crane then fell.

The Dutch TV channel NOS said the cranes fell on a second-hand clothing store and another shop selling art and drawing supplies, but it was unclear how many people were inside at the time.