A federal law enforcement source tells CNN that an arrest has been made in the Boston bombings investigation, CNN.com reports.
According to the source, the breakthrough in the case was a surveillance video from the Lord & Taylor department store near the location of the second explosion.
"[This is] the most complex crime scene that we've dealt with in the history of our department," Boston Police Commissioner Ed Davis said.
On Tuesday, the FBI revealed that one of the bombs appeared to have been made from a pressure cooker containing nails and ball bearings. They urged the public to send in tips, photos and videos from the scene.
The FBI is expected to have a briefing at 5 p.m./ET.