What's patrol police's task?

The law enforcement agencies are supposed to be the protector of people. But the current level of corruption and negligence of our police is quite alarming. Recently I witnessed a shocking event of hijacking. Two women were going by a rickshaw near Baily road when two hijackers on a motorbike sped up and snatched the purse of one woman and fled the scene. The helpless victims went to the nearby policemen on patrol for help. But surprisingly they said that it was not their duty to catch hijackers. If this is the response of the protectors, then who is safe in this country?
Shams Rashid
Dept. of EEE, BUET