Despite reports to the contrary there has not been an arrest in the Marathon attack.
There have been significant developments, as the FBI hunts whoever was behind the Boston bombs. Investigators believe they may have identified a suspect from CCTV footage.
ITV Correspondent Robert Moore reports from Boston:
Report of arrest made in the Boston bombings case, but is it not clear where or who or really how significant. An arrest is not proof of anything.
US media is reporting that an arrest has been made in connection with the Boston bombings. There is yet to be any official confirmation.
Reports of breakthrough in the Boston Marathon bombings should be treated with great caution. The FBI have seen CCTV from shop and one man is of interest.
The FBI have not identified this man and him leaving something on the ground makes him like - thousands of spectators - a man with a bag.
There is video taken from CCTV cameras at the Lord & Taylor shop apparently of a man leaving a bag at the scene of the second explosion. The FBI apparently consider video shot by a Boston TV station as significant. But CCTV from a department store is key new evidence.
Boston bombing investigators believe they have identified a suspect from security video taken before the blast, CNN and the Boston Globe reports.
"Substantial progress" is being made in the Boston bombings investigation, according to police officials.
White House Press Secretary Jay Carney has said the First Lady Michelle Obama will join the US President his visit to Boston tomorrow, following the marathon bombings.
US Secretary of State John Kerry became emotional today as he told congress that a friend's granddaughter is at risk of losing both of her legs following the Boston bombings:
He also told members: "It's impossible for me to express my sadness and my anger...over those terrible events. It's hard to believe a Patriots' Day holiday, which is normally a time of festivities, turned into bloody mayhem."
He added: "But we're going to find out who did this.The police work being done is extraordinary. The FBI is remarkable. There's a great deal of forensic evidence. We're hopeful that we can bring people to justice."
A Boston-based TV station, 7News, has released a photograph that appears to show a bag at the centre of one of the explosions in the city.
In the first image, a white bag can be seen by the side of the road:
The second image, taken some time after the blast, the bag is no long visible and debris litters the immediate vicinity. It has been blurred because of the graphic content.
The photographer who sent in the images said they were taken an hour or more apart.
According to the station, another series of images sent in by a viewer appear to show a man "fleeing from the scene" immediately following the blast.