Two explosions near the Boston Marathon finish line killed at least three people and injured more than 100 people Monday afternoon.

The blasts took place at about 2:50 p.m. Eastern time about 200 feet apart on downtown Boston’s Boylston Street. Federal authorities have been brought to the city to lead the investigation to determine the cause of the incident.

“It is a criminal investigation that is a potential terrorist investigation,” said FBI Special Agent Richard DesLauriers in a press conference broadcast Monday evening.

Additionally, a fire or explosion took place at Boston’s John F. Kennedy Presidential Library and Museum at about 4:15 p.m., though the Boston Police Department said that incident may have been a fire and may not have been related to the first two explosions. No one was injured in that incident.

Many of the blocks surrounding the blast site will be on lockdown through at least Tuesday as federal, state and local investigators canvas the area for additional information, while law enforcement will be conducting random searches on Massachusetts Bay Transportation Authority subway lines, Massachusetts Gov. Deval Patrick said during the press conference.

Both the 212-room Lenox Hotel and the 148-room Mandarin Oriental Boston, which are about a half-block and one block west of the finish line, respectively, were evacuated and closed by the Boston Police Department until further notice.

Mandarin Oriental spokeswoman Danielle DeVoe said that no injuries occurred at that hotel.

Additionally, the Fairmont Copley Plaza, which is about a block-and-a-half east of the explosions, is only letting guests and hotel employees into the building, the 383-room hotel said on its Facebook page.

The Federal Aviation Administration (FAA) has restricted air space over downtown Boston.

In Washington, Pennsylvania Avenue in the vicinity of the White House was evacuated and closed to pedestrians and vehicles on Monday afternoon as a precaution.

“We will find out who did this. We’ll find out why they did this,” President Barack Obama said in a briefing. “Any responsible individuals, any responsible groups will feel the full weight of justice.”