Authorities are investigating explosions near the Boston Marathon finish line.

The Fairmont Copley Hotel which serves as the headquarters for the marathon has been placed under lockdown while the investigation continues.

UPDATE (4/15/13 2:30 PM) The first blast happened at 2:50 Eastern time near the intersection of Boylston and Exeter streets and several storefronts were blown out.

About 15 seconds later a second blast took place across from the Lenox Hotel.

Witnesses are saying that several victims lost limbs in the blasts. Victims are still being treated at the scene and transported to local hospitals.

This is a breaking story with more details coming.