As of 4:25 P.M. MDT

Two explosions near the finish line of the Boston Marathon killed at least two people and maimed several others. The explosion happened about three hours after the race leaders crossed the finish line, according to the Associated Press.

A fire at the JFK Library is NOT related to the other explosions, according to the Boston Police Commissioner. There were no injuries in that incident. At a news conference, officials said the investigation is in its initial stages.

Google has suggested people looking for information on individual runners use their Person Finder site:

The Boston Marathon also has a telephone number for those looking for friends and relatives who were in the race - 1-617-635-4500.

President Barack Obama, responding to the explosions at the Boston Marathon, says the United States does not know "who did this or why" but vowed that whoever is responsible "will feel the full weight of justice...We will find out who did this and we will hold them accountable."

Obama made his remarks Monday evening from the White House about three hours after two explosions detonated near the marathon's finish line.

Police are urging Boston residents to stay indoors and not congregate in large groups. The Associated Press had initially reported that cellphone service was shut down in the Boston area to prevent any potential remote detonations of explosives, but retracted that report. Cell phone companies said service had not been interrupted, though cell traffic was heavy.

There is a toll-free tip line - 1-800-494-TIPS. If anyone has information as to the explosions, they are asked to call.

Officials at the news conference said that all parcels that have been discarded on the streets of Boston are being treated as possibly dangerous.

The Boston Bruins game and a concert by the Boston Symphony, both scheduled for Monday evening, were cancelled.