The deceased were identified as Ibrahim, Muhammad Aslam and Ishtiaq, police said, adding all the three were heading to New Sabzimandi.
Nine other persons in other vehicles were also suffered injuries in the accident. The injured were shifted to Abbasi Hospital.
Police said that as the tanker overturned, it caused an oil-spill on the highway which caused suspension of traffic on the road for about three hours.
In the second accident, a truck driver died when his truck overturned in Manghopir area.
Police said a speeding truck overturned when the front suspension of his truck broke down. Driver of the truck Manzoor died on the spot.
Police recovered the body and shifted it to Civil Hospital for legal formalities.
In another accident, an unknown man died in a hit and run accident in Gadap on Monday.
Police said the victim was in his mid-20’s when he was knocked down by an unknown vehicle. His body was shifted to JPMC for legal formalities, police said.