QUINTON, Oklahoma - From 2013 to 2017, the OSHA database shows Patterson UTI had more than two dozen "serious" penalties nationwide.

These penalties range from not having proper eye and face protection to not having appropriate medical services and first aid available.

It's still not clear what infraction, if any, could have caused Monday's gas rig explosion.

 "We will work with OSHA, and we have management teams working with OSHA today to begin the investigation,” said Patterson UTI CEO Andy Hendricks.

Three of the five men killed were Patterson employees.

"We want to learn from this,” said Hendricks. “We don't want this to happen again for anybody or for anybody in our industry."

News On 6 was able to count seven employee deaths since May 2009 on the OSHA database, but could not get a confirmed number from Patterson.

Hendricks says in a news conference that safety is the company's top priority.

"The safety of our employees and everyone at the well site is always the primary concern of ourselves, our management team, our employees, our company,” he said.

The representative from Red Mountain, the company operating the well, says they've never had anything like this happen.

News On 6 reached out to OSHA and Patterson, hoping to put the numbers in perspective, but didn't hear back.