Dense Fog in plain areas of Punjab disrupted air and road traffic in the morning as six international and internal flights could not land at the Allama Iqbal International airport on Tuesday and M-2 and M-3 Motorways were closed for several hours. The Motorway police have advised motorists to avoid unnecessary travels and use fog lights while driving as several persons were killed and injured in road accidents in central Punjab on Tuesday. Meanwhile Met-Office has predicted scattered rain with snowfall over the hills from Wednesday evening to Friday morning. It said a westerly wave is likely to grip western and upper parts of the country on Wednesday evening. Under the influence of this weather system, scattered rain with snowfall over the hills is expected in Islamabad, Khyber Pakhtunkhwa (KP), FATA, Upper Punjab (Rawalpindi, Sargodha and Gujranwala divisions), Gilgit-Baltistan and Kashmir. While isolated rain is also expected in Quetta and Zhob divisions during the period. The rain-fed areas of Punjab and KP may receive scattered rain of light to moderate intensity that will be very beneficial for the standing wheat crop. Met Office spokesman after this wet-spell, the low temperatures and high ground moisture will generate dense fog in the plain areas of Punjab, Peshawar valley and Sukkur division during the coming weekend. The dense foggy conditions would continue in the plain areas, particularly in Punjab, during next 3 to 4 weeks, affecting land and air traffic. NNI adds: As many as six people were killed and three sustained injuries in separate road accidents due to fog in parts of country on Tuesday. Dense fog covered several cities of Punjab, including Lahore, Sheikhupura, Muridke, Okara and Sahiwal, on night between Monday and Tuesday, causing problem in the flow of traffic on Motorway and other highways. A trailer was unable to judge the van coming from opposite side at Sheikhupura Road due to non-visibility and collided with the passenger bus, killing two people on the spot while injuring three others. On the other hand, four people were crushed to death after a speeding trailer hit a car in Darya Khan. Motorway's section from Lahore to Pindi Bhattian has been closed for all kinds of traffic as visibility was down to zero due to dense fog. The Motorway police have appealed the drivers to use GT Road for travel from Lahore to Pindi Bhattian. They have also urged the drivers to drive slowly and switch on fog lights. They also requested people to stay home and avoid unnecessary travelling. A severe disruption in flight schedule at Lahore s Allama Iqbal International Airport was also seen as visibility was down to zero. Several of the flights including Chief Minister Punjab's plane (PM) had to be redirected to other locations. Meanwhile, as many as 12 cars rammed into each other, injuring six people near toll plaza in Khanewal while five others also sustained wounds in a bus-van crash. The injured were shifted to the district hospital Khanewal for medical assistance.