An explosion at a residential building in the Swedish city of Gothenburg early this morning sent at least 25 people to the hospital.

According to a representative for Sahlgrenska University Hospital, four persons were critically hurt in the incident.

Three women in their 60s and 80s and a male in his 50s are among them.

According to emergency services, people were being evacuated, and fires were being put out in the building.

The tenants of the apartment tower have been evacuated in large numbers.

According to local media sources, fifty firefighters are on the scene following the explosion just before 5 a.m. local time.

"A number of apartments and stairwells have been impacted. It is now unknown what caused the explosion "According to the emergency services for the greater Gothenburg area.

The explosion was unlikely to have been caused by "natural causes," according to a rescue worker who spoke to TV4 Nyheter.

One firefighter was hurt while attempting to extinguish the flames and was taken to the hospital.

Some persons were alleged to have lowered themselves to the earth from windows by tying sheets together.

A 24-year-old inhabitant of the building stated he was awakened by a loud crash this morning.

Theodor Réus told the Swedish daily newspaper Aftonbladet that the pressure wave pushed his front door shut, and smoke billowed from the apartment.

"People were fainting on the ground when we got down to the courtyard," he claimed.

Pastor Daniel Dalemo of Saron Church, near the damaged structure, said he had invited 50 people to the church to offer assistance and support.

At other sites, city officials are also assisting people. Locals arrived in bathrobes, according to one worker, after fleeing the burning building.

According to a representative for the emergency services, several hundred individuals were evacuated from the area of the explosion and fire.

The origin of the explosion and fire was unknown at the time.

In recent years, the Nordic country has faced increased gang crime, with competing groups using explosives and firearms to settle scores.

Gothenburg is a significant city on Sweden's west coast with a population of 580,000 people.

An investigation has been launched, according to the police.