The break in an 8-inch water main was reported shortly after 2:00 p.m. on Erickson Avenue near the unit block of Becket Court.
The sidewalk collapsed and the street buckled due to the flooding waters.
Residents scrambled to get out of their homes as water came through.
Officials say 15 to 20 homes are without water service.
The Hockessin Fire Department is helping to pump water from basements.
An Artesian Water spokesperson says the break is likely cold related.
The water company has work crews on scene working on repairing the break and hopes to have the residents back in service tonight.
Delmarva Power also responded to check for possible gas leaks and to cut off power to some of the homes.
