Police were sent Friday to 262 public and private schools in the District of Columbia (search) after an Internet bomb threat that said devices had been planted at five schools.

Nothing suspicious was found.

"We get a lot of bomb threats in the schools and about other buildings," said Deputy Mayor for Public Safety Margret Nedelkoff Kellems (search), defending the decision not to evacuate schools or alert parents as students were dropped off Friday morning.

The threatening message was delivered to city police in an e-mail just before 6 a.m. It warned of explosions at five schools but did not specify which.