Businesses near a Citrus Heights industrial yard were forced to evacuate Thursday after heat-related issues caused a pressure problem in one of the company's propylene tanks, Sacramento Metro fire officials said.

Several businesses surrounding Harris Industrial Gases at 8475 Auburn Blvd were evacuated around 4 p.m. Thursday after employees noticed the problem with one of their 1,000 gallon tanks containing propylene, a highly flammable chemical often used as an industrial fuel.

Sac Metro Asst. Fire Chief Jim Eastman said the extreme heat caused an emergency valve to automatically open to relieve pressure from the expanding gas. However, the valve remained stuck open, bleeding the combustible chemical into the air.