Washington — The surviving Boston bombing suspect was identified as a 19-year-old man from Cambridge, Massachusets.
The Associated Press tweeted earlier that Dzhokhar A Tsarnaev is from a Russian region near Chechnya, and had lived in US for at least one year.
US network NBC News has reported that the two suspects are brothers.
Boston police said on Friday that all transit service by the Massachusetts Bay Transportation Authority "has been suspended until further notice" as a manhunt for a suspect in the bombing of the Boston Marathon was ongoing in a city suburb.
Vehicle traffic was also suspended in and out of Watertown, Boston police said.
The police department issued an advisory on Twitter about the closure of businesses. "Businesses in area of 480 Arsenal St in Watertown closed [till further] notice. Employees instructed to remain home."
An officer from Boston Police Department told the community, "We need your help now."
"This situation is grave," an officer stated, "we are here to protect public safety in these neighbourhoods."
The measures come as police continue to search for a second suspect in the Boston Marathon on Monday. "Suspect no.1" was shot and killed in a shootout with police after the two had killed a Massachusetts Institute of Technology (MIT) police officer on Thursday night.
Meanwhile, reports citing a White House official on Friday said US President Barack Obama was briefed overnight by a counter terrorism aide on the Boston bombing investigation and manhunt.