Updated, April 18, 6:07 p.m.
A federal official said authorities had identified the face of one man who they'd like to talk to about the bombing of the Boston Marathon but did not yet have his name.
The FBI has given law enforcement agencies a surveillance photo of a man wearing a baseball cap at the scene of the marathon bombing and is asking for help identifying the man, a senior federal law enforcement official who has seen the photo told NBC News.
The official who has seen the photo described it as showing a man about six feet tall, wearing a white or off-white baseball cap.
Investigators said Wednesday that they have identified "a number of people" who they would like to interview in relation to the bombing but had not made any arrests. "Contrary to widespread reporting, there have been no arrests made in connection with the Boston Marathon attack," the FBI said in a statement Wednesday afternoon.
Law enforcement officers cautioned that they are not prepared to call the people suspects or witnesses yet. However, authorities said they now possess "solid leads" in the case and have made "significant" progress.
Surveillance video from a Lord & Taylor department store camera showing a person placing a black bag near the scene of the blast led investigators to one of the people wanted for questioning, NBC News reported.
Investigators have said the bombs were contained in metal containers--at least one was a pressure cooker--and placed in black nylon bags.
The FBI is leading the investigation. As forensic teams continued to comb the 12-block radius around Copley Square after the bombings, the Boston Police Commissioner Edward Davis called "the most complex crime scene" in the history of the department.