U.S. offficials say images of at least one potential suspect in the Boston Marathon bombings have been captured from security video recordings.
However, the images have not been publicly released, and no arrests have been announced in connection with the April 15 bombings that killed three people and injured more than 170 others.
The FBI on April 17 denied several news reports that a suspect had been arrested.
The agency also cancelled a planned news conference about the investigation.
Officials earlier said the blasts are suspected of being caused by devices made from metal pressure-cookers.
President Barack Obama was expected to visit Boston on April 18 to pay tribute to the victims of the worst terrorist attack on civilians in America since the September 11, 2001, hijacked airliner attacks.
Based on reports from AP, AFP and Reuters