Officials on Saturday raised the death toll from a gas explosion in an apartment building in eastern Slovakia to seven.

Firefighters and the town hall of the city of Presov said one person is still missing.

The explosion occurred toward the top of the 12-story building on Friday. The entire top half of the building burned and the top three floors were destroyed, firefighters said.

Smoke billows from the building behind as officials view the scene, with from left, Minister of Defense Peter Gajdos, Prime Minister Peter Pellegrini and Interior Minister Denisa Sakova, at the site as emergency services work into the night after an explosion, and subsequent fire at an apartment building in Presov, Slovakia, on Friday Dec. 6, 2019. The explosion occurred toward the top of the 12-storey building and a spokeswoman for the rescue services said more than 40 people were injured. (Frantisek IvanTASR via AP)

Smoke billows from the building behind as officials view the scene, with from left, Minister of Defense Peter Gajdos, Prime Minister Peter Pellegrini and Interior Minister Denisa Sakova, at the site as emergency services work into the night after an explosion, and subsequent fire at an apartment building in Presov, Slovakia, on Friday Dec. 6, 2019. The explosion occurred toward the top of the 12-storey building and a spokeswoman for the rescue services said more than 40 people were injured. (Frantisek IvanTASR via AP)

Rescuers have said some 40 people were injured.

More than 100 firefighters tackled the blaze, which was finally fully extinguished on Saturday morning.

Prime Minister Peter Pellegrini, who visited the site late Friday, said the building is so damaged that it's possible it will have to be demolished.

Smoke billows as emergency services work into the night at the scene of an explosion, and subsequent fire at an apartment building in Presov, Slovakia, on Friday Dec. 6, 2019. The explosion occurred toward the top of the 12-storey building and a spokeswoman for the rescue services said more than 40 people were injured. (Frantisek IvanTASR via AP)

Smoke billows as emergency services work into the night at the scene of an explosion, and subsequent fire at an apartment building in Presov, Slovakia, on Friday Dec. 6, 2019. The explosion occurred toward the top of the 12-storey building and a spokeswoman for the rescue services said more than 40 people were injured. (Frantisek IvanTASR via AP)

People in surrounding homes also had to be evacuated.