A water main break on Broadway at Trowbridge Street brought out Cambridge police, fire and Department of Public Works employees late Saturday.

Police reported few details at about 10:30 p.m. Saturday, but warned area residents that their water pressure may suffer and asked motorists, bicyclists and pedestrians to avoid the area and seek alternate routes. A large section of Broadway has been shut down between Ware and Ellery streets. Trowbridge Street has also been closed from Harvard Street to Broadway.

The city was preparing to temporarily switch over to the Massachusetts Water Resource Authority water supply to offset the disruption caused by the water main break, police said Saturday. The city used its water supply to good advantage in May 2010, when a water main break forced thousands to boil their water before drinking it — but Cantabrigians escaped the troubles.