Boston's police, facing an upsurge in murder and other violent crimes, have set up a system to allow witnesses to tip them off to crime by sending anonymous text messages.

Boston Police Commissioner Edward Davis said the Text a Tip Program, announced on Friday, appeared to be the first in the nation to combine cell phone text messaging with an anonymous police tip line.

He said he hoped it would crack a street culture where gangs often punish people who snitch, making it hard for police to solve crimes at a time when the murder rate is rising.

It's something that is more anonymous than a telephone call where you have to have a conversation with someone, Davis said. A traditional tip line, using a toll-free telephone number to police, was becoming obsolete, he said.

Like many U.S. cities, Boston is struggling to stem a wave of violent crime. The city's 27 homicides this year are nearly on pace with last year's tally. Many go unsolved because witnesses are afraid to come forward.

In the new system, people with information about crimes would type the word tip into their phones and send the message to police. The sender's identification is blocked, Davis said. Police will then text a message back asking for details.

The announcement comes just days after a man whose brother was fatally shot in Boston's South End neighborhood was jumped by gang members who beat him while shouting stop talking to the cops, the Boston Herald newspaper reported.