WASHINGTON (CBSDC/AP) — A suspect has reportedly been arrested in the deadly Boston Marathon bombing.

CNN reports that a suspect has been arrested in the bombing that killed three people and injured 170 others near the Boston Marathon finish line. Officials confirm to CBS News that a suspect was identified in the video who appeared to be carrying a black bag with the bomb near the Boston Marathon finish line.

Earlier, CNN and The Boston Globe reported that authorities had an image of the suspect carrying a bag that was dropped near the finish line.

CNN reports that video from a department store near the blast and from a Boston television station helped in the process. CNN’s John King reports that officials told him that surveillance video from a Lord & Taylor near the blast scene was key in helping to identify the suspect.

Officials tell The Associated Press that the suspect is to be taken into custody by federal marshals and taken to a courthouse.

The Federal Bureau of Investigation will be holding a briefing at 5 p.m. ET.

Authorities a piece of circuit board that they believe was part of one of the explosive devices, and also found the lid of a pressure cookerthat apparently was catapulted onto the roof of a nearby building, an official said Wednesday.

A law enforcement official briefed on the investigation confirmed to The Associated Press that authorities have recovered what they believe are some of the pieces of the explosive devices. The official spoke on condition of anonymity because this person was not authorized to publicly discuss evidence in the ongoing investigation.

A person close to the investigation previously told AP the bombs consisted of explosives put in 1.6-gallon pressure cookers, one with shards of metal and ball bearings, the other with nails.

Investigators in white jumpsuits fanned out across the streets, rooftops and awnings around the blast site in search of clues on Wednesday. They combed through debris amid the toppled orange sports drink dispensers, trash cans and sleeves of plastic cups strewn across the street at the marathon’s finish line.

Also Wednesday, a doctor at Boston Medical Center said two patients, including a 5-year-old child, remain in critical condition there. Dozens of others have been released from hospitals around Boston.

Law enforcement agencies pleaded Tuesday for the public to come forward with photos, videos or any information that might help them solve the twin bombings that killed three people and wounded more than 170 a day earlier. Investigators circulated information about the bombs, which involved kitchen pressure cookers packed with explosives, nails and other lethal shrapnel — but the FBI said nobody had claimed responsibility.

“Someone knows who did this,” Richard DesLauriers, FBI agent in charge in Boston, said at a news conference where he detailed the type of clues a bomber might have left. “Importantly, the person who did this is someone’s friend, neighbor, co-worker or relative.”

President Barack Obama branded the attack an act of terrorism.Obama plans to attend an interfaith service Thursday in the victims’ honor in Boston.

Scores of victims of the Boston bombing remained in hospitals, many with grievous injuries. Doctors who treated the wounded corroborated reports that the bombs were packed with shrapnel intended to cause mayhem. In addition to the 5-year-old child, a 9-year-old girl and 10-year-old boy were among 17 victims listed in critical condition.

The trauma surgery chief at Boston Medical Center says most of the injuries his hospital treated after the marathon bombings were to the legs.

“We have a lot of lower extremity injuries, so I think the damage was low to the ground and wasn’t up,” Dr. Peter Burke said. “The patients who do have head injuries were blown into things or were hit by fragments that went up.”

Dozens of patients have been released from hospitals around the Boston area.