At least five people were killed and 20 injured in a blast in Pakistan’s Karachi city on Wednesday, Dawn reported, citing rescue officials.

The blast took place near Maskan Chowrangi in the city’s Gulshan-i-Iqbal area, officials of Edhi Foundation said, adding that all the injured and the deceased were taken to Patel Hospital. The police have cordoned off the area.

Initial reports said the blast occurred because of gas leakage, adding that no traces of an improvised explosive device was found. However, a bomb disposal squad was at the scene investigating the exact cause of the explosion. It has found a burner of a stove and pieces of metal from the site.

Karachi Administrator Iftikhar Shallwani also said the cause of the blast cannot be determined till an inquiry is conducted. Pakistan Peoples Party minister Saeed Ghani, who visited the blast site, reiterated Shallwani’s statement and said it could not be yet determined if it was a terrorist attack.

Video footage from the spot showed that the building was badly damaged. Witnesses told the newspaper that windows of nearby buildings and some vehicles were also damaged.

Sindh Chief Minister Murad Ali Shah has directed the Karachi commissioner to submit a detailed report on the matter and asked authorities to ensure medical treatment for those injured. He also expressed grief over the deaths.

Pakistan Peoples Party Chairman Bilawal Bhutto-Zardari also expressed grief over the deaths, a party statement said. Federal Minister for Maritime Affairs Ali Zaidi offered “prayers and sympathies” to the victims and asked the authorities to conduct a thorough investigation.

On Tuesday, five people were injured when a bomb went off at the entrance of a bus terminal near Sheerin Jinnah Colony in Karachi.