Now you see it, now you don't.

A segment of a bridge in Raigad district, some 100km south of Mumbai, disappeared after collapsing yesterday.

Two buses carrying at least 22 people plunged into the fast-flowing River Savitri after the collapse, which happened following days of torrential monsoon rains, Indian officials said.

The buses were on their way to Mumbai when the older of two parallel bridges on the Mumbai-Goa highway, said to have been built under British rule, collapsed, media reports quoted witnesses as saying.

Mr O.P. Singh, chief of the state-run National Disaster Response Force (NDRF), said 80 rescuers, including divers, had rushed to the area but their efforts were being hampered by heavy rains.

"We have not even spotted the buses so far," said Mr Rakesh Ranjan, deputy commandant of operations at the NDRF.