A teenager was killed and several other people injured when protesters stormed the U.S. embassy, the Pakistan News Agency reported.
The shots were reportedly fired from the embassy. However, embassy officials denied they took part in the shooting.
Police used water cannon to prevent the demonstrators from reaching the embassy. The police also used tear gas and fired into the air, the news agency said.
Protesters threw stones at police and set fire to a checkpoint near the embassy, Geo News reported. Some of the rocks landed inside the embassy building.
At least six people were injured in clashes with police.
Two other men were killed and another hurt in separate incidents around the city, which saw protesters set fire to a dozen bicycles, two mobile police units, two banks and two fueling stations.