Policeman honoured for hunting Boston Marathon bombers shot in face

A policeman honoured for helping pursue the terrorists who attacked runners and spectators at the 2013 Boston Marathon has been shot in the face and is in an induced coma, authorities said.

Officer John Moynihan, 34, was wounded in Boston on Friday night during a routine traffic stop, Efe news agency cited police Commissioner William Evans as telling a press conference.

After being stopped, the car's driver opened fire on Moynihan and other agents at the scene, until he was gunned down by police.

In the shooting, Moynihan took a bullet below his right eye, a woman who was passing by was shot in the arm, and three other cops required medical care for problems of stress.

"The officer here is in tough shape, but we're all pulling for him, and hopefully he'll pull through. His family's with him, the clergy has been here and... let's pray for him," Evans said.

On his part, Boston Mayor Marty Walsh condemned the attack and said "these acts of violence have no place in our neighbourhoods".

Moynihan, a war veteran who served in Iraq, was decorated last May in the White House for his role in hunting down the brothers Tamerlan and Dzhokhar Tsarnaev, perpetrators of the Boston Marathon bombing in April 2013.

The brothers planted two homemade bombs that killed three people and wounded 260 at the finish line of the race.

In their attempted escape through Boston and its outskirts, the perpetrators of the attack killed a policeman on the campus of the Massachusetts Institute of Technology (MIT) after which the movie-like chase began with a driver being kidnapped, homemade explosive devices tossed and shootouts in residential areas.

While Tamerlan was killed in a clash with the cops, police managed to corner Dzhokhar in a boat behind a house in Watertown after an almost 24-hour hunt.

The trial charging Dzhokhar Tsarnaev and his late brother with planting the two bombs began on March 3.