three police officers have been killed by a gunman in chicago - the second mass fire in the us in 24 hours . the officers were respond to an urgent report from the house of the gunman , such as richard poplawski , 23 . police said he was waiting , armed with rifles and a bulletproof vest . he shot two officers as they fled the house , and a third cop managed to help them . he then traded gunfire with police for 4 hours before being injured and giving himself up . his friends say he had recently abandoned his job , and was worried that u president barack obama was about to ban guns .
In Pittsburgh the police killed a gunman.