An “opacity event” in the form of a yellow gas cloud occurred at the Commerce City Suncor plant on Tuesday evening, which state officials believed did not present an ongoing risk.

Approximately 5:40 p.m., a clay-like catalyst was released during an equipment malfunction, Suncor said in a statement. The energy company, based in Alberta, said that it sounded a vapor release alarm, notified state and local authorities, and shut down Brighton Boulevard temporarily.

The Colorado Department of Public Health and Environment stated that Suncor used handheld devices to measure hydrogen sulfide and sulfur dioxide, two toxic gases. Employees did not detect any elevated levels and CDPHE did not believe there to be “an ongoing risk to the community.”

“We will monitor the situation and review data from the air monitors we have placed around the Suncor refinery,” the department said.

Suncor’s statement on Tuesday night promised that the company would “provide more information as it becomes available and as response activities allow.” As of Wednesday morning, there was no further update.

Earlier this month, the state reached a $9 million settlement with Suncor over more than 100 air quality violations from the Commerce City facility.

The Colorado Latino Forum issued a statement after the opacity event, slamming the “tepid response by Suncor” and decrying the lack of “a clear statement that any and/or all employees are safe and out of harm, no real communication to the surrounding community other than a Facebook post, and no real safety response to the community they should be accountable to.”

While Suncor said that all employees were “accounted for,” it did not mention whether all employees were in healthy condition. The company did not immediately respond to an inquiry from Colorado Politics, but posted on Facebook on midday Wednesday that the downwind air monitors have not shown any concerning readings.

“We have launched an investigation to determine the exact cause of the air blower trip,” Suncor wrote in its update. “We need to understand this information prior to a safe re-start.”

A pending bill in the General Assembly sponsored by the legislators representing the Suncor area would require the public release of air monitoring data from applicable facilities and establish a real-time alert mechanism for pollution incidents, among other enforcement protocols. The legislature is on hiatus during the coronavirus outbreak.

Editor’s note: This story has been updated with response from Suncor.