Grammar?

Put in articles and prepositions where necessary to complete the passage: We received 11) ___ emergency call at 3.15 a.m. which said the Grove Hotel was 12) ___ fire. We were at the scene within fifteen minutes. The first and second floors of the hotel were in flames when we arrived. But we succeeded 13) ___ getting the fire under control after two hours. I was in 14) ___ charge of the whole operation. Two of our people are still in hospital being treated 15) ___ the effects of smoke inhalation. At 16) ___ moment it appeared that the fire had started by 17) ___ accident, but it is still not clear why the fire spread so quickly or why the third floor burst 18) ___ flames.

Put in articles and prepositions where necessary to complete the passage: We received 11) an emergency call at 3.15 a.m. which said the Grove Hotel was 12) in fire. We were at the scene within fifteen minutes. The first and second floors of the hotel were in flames when we arrived. But we succeeded 13) in getting the fire under control after two hours. I was in 14) _a charge of the whole operation. Two of our people are still in hospital being treated 15) for the effects of smoke inhalation. At 16) the moment it appeared that the fire had started by 17) an accident, but it is still not clear why the fire spread so quickly or why the third floor burst 18) _in flames.

fold paint 63

Put in articles and prepositions where necessary to complete the passage: We received 11) an emergency call at 3.15 a.m. which said the Grove Hotel was 12) on fire. We were at the scene within fifteen minutes. The first and second floors of the hotel were in flames when we arrived. But we succeeded 13) in getting the fire under control after two hours. I was in 14)- charge of the whole operation. Two of our people are still in hospital being treated 15) from the effects of smoke inhalation. At 16) the moment it appeared that the fire had started by 17) - accident, but it is still not clear why the fire spread so quickly or why the third floor burst 18) into flames.

fold paint 63

Put in articles and prepositions where necessary to complete the passage: We received 11) _an emergency call at 3.15 a.m. which said the Grove Hotel was 12) _on__ fire. We were at the scene within fifteen minutes. The first and second floors of the hotel were in flames when we arrived. But we succeeded 13) _in__ getting the fire under control after two hours. I was in 14) a___ charge of the whole operation. Two of our people are still in hospital being treated 15) with___ the effects of smoke inhalation. At 16) _the moment it appeared that the fire had started by 17) ___ accident, but it is still not clear why the fire spread so quickly or why the third floor burst 18) _into__ flames.

an,on,in,,with,the,,into

We received an emergency call at 3.15 a.m. which said the Grove Hotel was on fire. We were at the scene within fifteen minutes. The first and second floors of the hotel were in flames when we arrived. But we succeeded in getting the fire under control after two hours. I was in charge of the whole operation. Two of our people are still in hospital being treated by the effects of smoke inhalation. At the moment it appeared that the fire had started by accident, but it is still not clear why the fire spread so quickly or why the third floor burst into flames.

I'm curious to know the correct answers especially for these parts:

fold paint 63but it is still not clear why the fire spread so quickly or why the third floor burst 18) ___ flames

Some posters answered it with "in" and others with "into", which one is correct?

fold paint 63the Grove Hotel was 12) ___ fire.

I think it's "on", but there are some responses wrote "in", which one is correct?