An explosion that occurred in a restaurant Monday in the city of Antwerp, Belgium, led to the collapse of a residential building and damage of multiple other buildings, injuring at least ten to 20 people, police authorities said.

The blast took place at Italian restaurant Primavera, situated in the area of Paardenmarkt, a place inhabited by University of Antwerp students. The Antwerp police said the blast was believed to have been caused by a gas leak. The authorities also notified it had no connection to any terror activity.

After the blast, the fire brigades were summoned approximately around 9:30 p.m. UTC (4:30 p.m. EST), Belgian newspaper Het Nieuwsblad reported. Multiple buildings including Primavera, where the blast happened, were severely damaged.

Six building were announced as uninhabitable. Fourteen people were wounded, out of which five were in serious conditions and one in a critical condition. The other eight were injured but were not critical. 

The report further stated numerous people were trapped under the debris of the residential building that collapsed. The police authorities, with the help of police dogs, were able to pull out several people, according to a report by the Independent.

The Paardenmarkt area was completely shut down after the incident. Along with the fire brigades, the Red Cross also established a tent at the scene.

The report added, according to the accounts given by witnesses, the blast was loud, with one student saying, “The bang was so big that my window opened. … It was a huge explosion.”

Another witness, Catherine, who lived around the corner from the scene of the incident, said, “I felt the ground vibrate, I saw two fire engines and at least five combis.” She added the effect of the blast was felt up to the second floor.

The report said transportation service provider De Lijn Antwerpen offered shuttle buses, which transported people, whose houses were damaged, to a place where they would be taken care of. Approximately at 2 a.m. UTC (9 p.m. EST), the people who resided within the safety perimeter area were permitted to return to their homes. The students also provided shelter to the affected ones. 

The residents of house numbers 97 to 103A, which suffered damages due to the blast, were provided with appropriate care and assistance.

The incident occurred in a student locality and that too during the time of examinations. Peter De Meyer, spokesman for the University of Antwerp, said the affected students will be contacted Tuesday, and then the appropriate measures will be taken. De Meyer also stated the students who have oral examination can alter the time of the exam. However, the written examinations weren’t postponed.

According to a report by RTBF, a public broadcaster in Belgium, the Italian restaurant was situated under one of the buildings that also consisted of residential apartments.

The mayor of Antwerp, Bart De Wever, took to Twitter to offer his support to the victims and families.