At least 26 people have been killed in an attack by suspected militants in India-controlled Jammu and Kashmir, according to officials, in an incident that the restive territory’s chief minister said was the deadliest against visitors in decades.

Tuesday’s assault in the popular destination of Pahalgam is a setback for the government of Prime Minister Narendra Modi, which has claimed to have brought peace to Jammu and Kashmir since downgrading what was India’s only Muslim-majority state to a territory under direct federal rule.

It could also increase tensions between India and Pakistan, which backs Kashmiri separatism. The territory is part of a region that is also claimed and partially controlled by Islamabad and has been a long-running flashpoint between the nuclear-armed neighbours.