Thick smog and the resultant low visibility in the National Capital Region today led to two accidents in which five persons were killed and seven others injured. The Met Department said, visibility was reduced to 300 metres in the morning as thick smog created by smoke and fog descended in the wee hours of the day. The visibility later improved to 1,000 metres at around two pm. The smog continued for long as there was no wind. Weatherman said that foggy condition will persist for two-three days. Seven students were injured when a school bus was hit by a truck at around 7.30 am near Kashmire Gate area in Delhi due to low visibility. According to police sources, students of DPS Mathura Road were getting into their mini-bus when the truck hit the vehicle from behind. Three girls and four boys sustained injuries as the vehicle overturned, They were immediately rushed to Bara Hindu Rao Hospital. <br/><br/>In a separate accident, five railway men, including an officer, were run over by Delhi-bound Dehradun Janshatabdi Express near Ghaziabad at around 11.30 am. Poor visibility was believed to be the cause of the mishap.