Authorities are reporting that a 29-year-old French national in Australia on a tourist visa has been arrested following the fatal stabbing of a 21-year-old British woman at a backpackers’ hostel Wednesday. A 30-year-old British man is in critical condition, and a dog was also killed in the attack.

A police spokesman said the suspected attacker shouted “Allahu Akbar” when arrested. He is believed to have acted alone.

Police say the attack happened in front of at least 30 witnesses.