A fire broke out at a hotel in the port city of Busan Tuesday morning, prompting some 170 guests to evacuate or seek rescue.

According to Busan’s fire and disaster headquarters, the blaze started from an underground floor at the hotel located in Haeundae District at around 9:34 a.m. and was automatically reported to authorities through a detection device.

Authorities issued a level-one response and mobilized 300 firefighters, five helicopters and 77 vehicles in a rescue-and-extinguish operation, with choppers and ladder trucks used to rescue guests from hotel balconies and the rooftop.

Officials put out the fire completely by 1:30 p.m.

As of 1 p.m., 31 guests had been sent to the hospital for smoke inhalation, with firefighters combing through rooms and the basement to look for other guests or hotel employees.

An onsite director from the Haeundae Fire Station confirmed that the blaze likely started at a waste disposal site on the sixth basement floor and a joint probe will seek to determine the exact cause.

The hotel is situated in a 30-story building with seven underground floors that also houses restaurants.