A 35-year-old man allegedly murdered 14 members of his family, including seven children, with a butcher’s knife before committing suicide outside India’s financial capital of Mumbai, police said on Sunday.

The attack happened after family members gathered late on Saturday at one of their homes in Thane, some 32 kilometres (20 miles) from Mumbai, for a family function, police said.

“The attacker, Hasnin Anwar Warekar, hung himself after slitting the throats of all other family members including his parents,” a Thane police spokesman, Gajanan Laxman Kabdule said. The sole survivor of the attack – Warekar’s sister – was taken to hospital after neighbours heard her screaming for help after midnight and alerted police.

“We still haven’t been able to speak with the attacker’s 21-year-old sister, the lone survivor of the attack, who is in deep trauma at a city hospital,” Kabdule said. Warekar attacked his family after apparently lacing their food with a sedative, according to several local media reports.