The earthquake that shook much of the East Coast cracked one of the stones at the top of the Washington Monument, a National Park Service spokesman said on Wednesday.
The huge obelisk, a prime tourist attraction on the U.S. capital's central Mall, was evacuated soon after the quake was felt around 1:51 p.m. EDT on Tuesday.
The crack in one of the stones in the monument's pyramidium -- the pyramid shape at the very top -- was detected during an inspection by helicopter, spokesman Bill Line said.
Structural engineers are expected to make further assessments on Wednesday. The monument remains closed until further notice, Line said.
Public schools in the District of Columbia were closed on Wednesday as officials make safety assessments of the 126 school buildings, city officials said in a statement.