Obama in Boston for marathon bomb victims' service

US President Barack Obama arrived in Boston on Thursday to attend a special service for the victims of the bomb attack at the city's marathon.

Obama was to attend an inter-faith service at Boston's Cathedral of the Holy Cross three days after the attack, in which three people were killed and about 180 injured.

Mitt Romney, the former Massachusetts governor who lost to Obama in the presidential election last year, was also at the cathedral, along with city leaders and rescuers and victims from the blast.