At least five people have been killed in an explosion outside a major Sufi Muslim shrine in the Pakistani city of Lahore, officials said.
Many are feared injured according to local news broadcaster Geo News, which said a police vehicle had been hit.
The blast occurred near the Data Darbar Sufi shrine, one of the oldest Muslim shrines in South Asia.
It comes as the country marks the Islamic holy month of Ramadan.
A security operation is under way in the area with heavy police presence at the blast site.
No group has said it carried out the attack.
The shrine is located inside the ancient Walled City in Lahore, Pakistan's second-biggest city.
It is visited by hundreds of thousands of people each year from both Sunni and Shia traditions of Islam.
Sufism is a form of Islamic mysticism existing across the Islamic world and includes both Sunnis and Shias.
Its followers in Pakistan have been attacked by militants in the past.
In 2010, dozens died in two suicide blasts at the Data Darbar shrine.