Published: May 05, 2010 6:00 PM EDT

BILLERICA, Mass.  - Two children have been taken to the hospital as a precaution after a minivan driven by a pregnant woman crashed into a suburban Boston day care center.

Authorities say about 100 children were in the building when the minivan crashed into the KinderCare Learning Center in Billerica just before 9:00 a.m. on Wednesday.

The children and staff left the building after the crash. The ages of the children taken to the hospital were not released. Deputy Fire Chief Tom Ferraro says damage to the building was so extensive that it was condemned.

The cause remains under investigation but police say the woman's foot may have slipped off the brake and hit the gas pedal as she dropped off her child. Her name was not immediately released.