An underground vault explosion forced several buildings in downtown St. Louis to be evacuated Tuesday night.

According to Ameren officials, a transformer exploded near the intersection of 10th and Olive around 6:30 p.m. It was caused when a cable failed, the utility said.

“My entire building is made out brick and we have cement floors and it felt like something hit the building, our entire building shook,” said Karri Boumann, an area resident.

At least three nearby buildings were evacuated. All residents have been allowed back inside the buildings.

Fire crews were able to put out the fire quickly, allowing the roadway to reopen.

Some people were without power for a short time, but it has since been restored.

Ameren says the age of grid is one reason why the fire occurred.

"Some of the equipment dates back all the way to around 1900, the equipment that failed last night was from the 1940s," said David Wakeman, Sr. Vice President of Ameren.

Ameren also said the heat in June contributed to the fire. Ameren crews are installing a new transformer at 10th and Locust.

The new transformer will cost $60,000. It is just part of the $25 million a year budget for grid updates.

During the third week of June, a portion of 7th and Market was closed and there were widespread power outages after an electric fire started in a manhole.

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