Scissor lifts can be dangerous if not used properly. That point was made again by an Oct. 4 accident at a Frito-Lay North America facility in Irving, Texas, where a worker in a lift died and two others were badly injured in construction-related work.

The nature of what was being done is unclear. The employer is a specialty contractor, Walker Industrial. According to the company website, it provides automation and other industrial services. Local media gave the name of the

A spokesman for the Irving Police Dept. initially described the accident as a collision between two ladders. He added that the workers fell about 30 feet. One of the injured was in critical condition. Local media stated that the man who died was Hernan Murillo.

In a statement, Walker Industrial said it is investigating the accident and that its “deepest sympathies are offered to the families of everyone impacted by this incident.”

A spokesman for the regional Occupational Safety and Health Administration’s office said that an investigation is underway.

The stability of fully extended scissor lifts has long been a concern. Safety regulators have pointed to hazards in uneven ground, overloading and accidental contact with controls. In an accident on a high-rise building construction project in Oklahoma City in 2016, a scissor lift operator tumbled to his death by falling from the building.

According to The Center for Construction Research and Training, on average, 26 construction workers die each year while using aerial lifts of all kinds.

Third-party liability lawsuits often hit dealers and manufacturers after such accidents, says David Kwass, a personal injury attorney in Philadelphia.

There are numerous sources of information about how to work safely with scissor lifts. Among them are the Statement of Best Practices for Workplace Risk Assessment and Aerial Work Platform Equipment Selection, published by several different organizations including the Association of Equipment Manufactures (AEM). In addition, every aerial lift rental comes with an owners/operators manual, an ANSI Manual of Responsibilities, and an AEM Safety Manual. Each facility typically has its own list of site-specific aerial lift rules, too.