At least four persons were injured after robbers opened fire at a passenger bus here in Khanewal on Saturday morning. According to police, armed dacoits signaled to stop a Sargodha bound passenger bus coming from Multan at Jhang Road near Adda Nabipur area of Kabirwala. As the bus got slower after driver applied brakes, the armed men started firing at the bus injuring four passengers and fled from the scene. The injured passengers were shifted to Tehsil Headquarters Hospital Kabirwala where according to hospital sources condition of all the passengers was out of danger. The police reached the scene after the firing incident and started search for the attackers but they managed to flee safely.