Lahore: A suicide bomber killed at least 53 people and injured over a 100 outside a public park in the eastern Pakistani city of Lahore on Sunday, rescue officials and police said, striking at the heart of Prime Minister Nawaz Sharif's political heartland of Punjab.

Iqbal Town Superintendent of Police Dr Muhammad Iqbal said the explosion was a suicide attack and took place in a children's park, where a large number of families, especially women and children, were present on a Sunday evening, reported dawn.com.

The blast occurred in the parking area of Gulshan-e-Iqbal Park, just outside the exit gate and a few feet (metres) away from children's swings. 

Eye witnesses said there were pools of blood and scattered body parts in the park.

An eyewitness, talking to DawnNews, said dead bodies and injured were on the ground everywhere.

"We took the injured to hospitals on rickshaws and taxis."

He said the crowd was "unusually large" because of Easter. "The roads were also jammed and queues of vehicles could be seen till Moon Market."

Many eyewitnesses said there was no security present in and around the park. A man, talking to DawnNews, said:

"The park is huge and has many entrance gates. There was almost negligible security personnel present there."

Rescue officials and police rushed to the explosion site in a renowned residential area of Lahore.

Rescue 1122 spokesman confirmed that an emergency call was received at around 6:44pm and that 23 ambulances are present at the site.

An emergency has been declared at all government hospitals in the city, and a heavy contingent of police has cordoned off the area.