PLEASE NOTE: THIS EDIT CONTAINS CONVERTED 4:3 MATERIAL<br/> <br />A suspect at the centre of the Boston Marathon bombing is on the run after a major police operation was launched in a city suburb.<br/> <br />Officers descended on Watertown on Thursday night (April 18) just days after explosions in Boston killed three people and left over 170 wounded.<br/> <br />The suspect wanted by police is pictured here in the white cap.<br/> <br />Officers say he is dangerous and has come "to kill".<br/> <br />The second suspect, pictured here in the black cap, was shot dead as police pursued the men.<br/> <br />Boston officials have urged residents to remain inside as the incident is ongoing.
