Islamabad, Pakistan (CNN) -- An explosion in a house in southern Pakistan killed six people Friday morning, police said.
The blast happened in the town of Baldia, said Karachi police chief Wasim Ahmed.
Two injured survivors were taken into custody, Ahmed added.
Police were investigating, but seven grenades and an AK-47 assault rifle were found in the home.
The house might have been used by a terrorist group, Ahmed said.
Journalist Nasir Habib contributed to this report.