QUINTON, Okla. — Drilling company officials ignored multiple warnings that safety equipment at an Oklahoma gas well was malfunctioning before an explosion that killed five workers and badly injured another, the family of one of the dead workers contends in a recent court filing.

Parker Waldridge's family alleges in a Dec. 4 amendment to their wrongful death lawsuit that a "cascade of errors and multiple departures from safe drilling practices" by drilling company Patterson-UTI Drilling led to the Jan. 22 blowout near Quinton, which is about 125 miles east of Oklahoma City.

The lawsuit alleges that at least two days before the explosion, the rig superintendent, manager and several other Patterson employees received email results of a laboratory test warning of problems with the rig's accumulator, a piece of safety equipment that closes part of the well to prevent an uncontrolled release of fluids. The warnings even came with a "skull and crossbones graphic (literally)," the lawsuit said.

The accumulator wasn't able to fully close the well on the day of the blast, the U.S. Chemical Safety and Hazard Investigation Board found.

"Patterson Drilling had the most direct control over the drilling operations and emergency response to changing conditions and failed to use ordinary care with respect to its conduct," the lawsuit alleges.

Red Mountain Energy, which owns the well and hired Patterson to work it, issued a statement saying that Patterson's "gross negligence led to a terrible tragedy."

"The facts cited in the amended petition demonstrate exactly which parties failed to perform basic safety procedures prior to this accident," said Red Mountain, which is also a defendant in the lawsuit.

Patterson, meanwhile, issued its own statement, calling Red Mountain Energy's allegations "inflammatory" and blaming the company for the well's design and drilling program.

"It is important to note that Red Mountain was the lease holder and operator of the well, which was drilled under its direction, supervision and control," Patterson said."

Killed in the explosion were Waldridge of Crescent; Matt Smith of McAlester; Roger Cunningham from Seminole; Josh Ray of Fort Worth, Texas; and Cody Risk of Wellington, Colorado. Autopsies determined all five men died of burns and smoke inhalation. The families of each dead worker and Kevin Carrillo, who was badly injured, have filed lawsuits over the explosion, The Tulsa World reported.

The explosion was the deadliest drilling accident since the Deepwater Horizon rig exploded in the Gulf of Mexico in 2010, killing 11 people.