The uncle of the two suspects in Monday's Boston Marathon bombings on Friday denounced the terrorist act of his nephews, and urged the one still at large to surrender to authorities.

The bombings "put a shame on our families" and "on the entire Chechen ethnicity," Ruslan Tsarni said to a group of reporters live on TV near his residence in Montgomery Village, Maryland.

Tsarni is the uncle of Tamerlan and Dzhokar Tsarnaev, who were identified by the Federal Bureau of Investigation (FBI) on Thursday as suspects in Monday's twin blasts near the Boston Marathon finish line that left three people dead and over 170 injured. The family was said to have come from a Russian region near Chechnya.

The 26-year-old Tamerlan was confirmed dead at a local hospital with multiple gunshot wounds after a shootout with the police earlier on Friday. Dzhokar, 19, is still on the run and is the target of a massive manhunt that resulted in the lockdown of the whole Boston area.

Tsarni, who appeared quite emotional on TV, said that he would call his nephews "losers" if they were really guilty of the bombings.

"If you are alive, turn yourself in," he appealed to Dzhokar, who he said should ask for forgiveness from the victims of the bombings as well as their families.

Starting Friday morning, authorities have suspended all public transportation in the Boston region for the manhunt. Local residents were advised to stay at home and keep their doors locked.

At a brief press briefing shortly after noon, Massachusetts and Boston officials asked the people to remain indoors as the search for Dzhokar is still underway.

State police said that there is no apprehension yet while officers are going door to door to continue the manhunt.