Suspected street gang members have killed a policeman in El Salvador, the fifth officer to die in attacks this week.

The National Civil Police communications office said Friday that an officer was shot by two men at a police post in the township of San Ignacio in the department Chalatenango, which borders Honduras.

Four officers were slain in three earlier attacks this week. Since January, gangs have killed 40 police officers, a police mechanic, 15 soldiers, six prison guards and a prosecutor. In all of 2014, 39 police officers were killed.

Authorities say the gangs are trying to pressure the government to negotiate a treaty with the gangs like a previous one that saw the homicide rate drop precipitously. The government has said repeatedly it will not negotiate with criminals.