Texas City lifts shelter-in-place after chemical release earlier Sunday

A city in Texas has lifted a shelter-in-place after a "temporary increase in sulfur dioxide emissions" earlier Sunday at the Marathon Galveston Bay Refinery.

"The shelter-in-place has now been lifted. All roadways are open, and there is no longer a need to shelter in place," the city said in an updated news alert on its website. "Multiple agencies have been conducting air monitoring, and all readings in the affected areas and throughout the city are normal. We will continue to monitor the situation closely."

Personnel at the refinery "have resolved an operational upset that had led to a temporary increase in sulfur dioxide emissions earlier today," Marathon Petroleum Corp. said in a statement. "Emissions have returned to normal levels."

No injuries have been reported.

Earlier Sunday, the city issued a shelter-in-place for residents in "the area south of FM-519 to the Texas City Y" and said at the time the affected roads were loop 197, the 519 at the 149, and 4th Avenue South at loop 197.

"If you are in the affected area, please remain indoors with all doors and windows closed, and turn off your heat or A/C until further notice," the city had said. "Several intersections are barricaded, and traffic is not allowed through. Please avoid the area at this time."

In a subsequent update, the city said it continues to closely monitor the situation, adding: "At this time, there are no air monitoring readings that indicate danger to life or health."

"There have been no injuries. Air monitoring has been deployed in the community, and the City of Texas City has issued a shelter-in-place for an area south of the refinery," Marathon Petroleum Corp. said in a previous statement.

"The safety of personnel and the public is our top priority as we work to resolve the situation," it added.

ABC News' Vanessa Navarrete contributed to this report.