An ammonia leak at an ice cream plant spewed gas into the air on Saturday, forcing authorities to evacuate 30 people from their homes as they tried to find the source of the leak.

“You can see the clouds of ammonia, a white cloud, blowing right across the street,” said Dick Osborne, general manager of radio station WKXL.

After the leak was discovered at 9:20 a.m., about 30 people were evacuated to the nearby state prison and were expected to spend the night with friends, family or in hotels.

More than 12 hours after the leak was reported, the source of the leak had not been found and the area was still closed to traffic.

Fire Chief John Dionne said the main danger was from inhaling the fumes, but with hazardous levels of gas outside the plant, there was also the possibility of fire or explosion.