Follow CBSDFW.COM: Facebook | Twitter

ARGYLE (CBSDFW.COM/AP) — Federal regulators have cited two companies in the deadly collapse of an under-construction steel structure at a North Texas school.

Julio Ledesma, 36, was killed and three hurt in the April 2 steel framework collapse at the site of an activity center for Argyle High School, 20 miles north of Fort Worth. No students or school staff members were near the structure at the time of the collapse. About 15 workers in all were on site at the time of the collapse. They were building Argyle High’s new indoor athletic center.

The project had been under construction for about three months when the accident happened.

The Occupational Safety and Health Administration in September said Northstar Builders Group and Warnick Metal Building Erectors failed to maintain structural stability. Each company was found to have committed a serious violation and fined $7,000.

Court documents the CBS 11 News I-Team uncovered show Warnick Metal was sued in 2007 after a building they put together collapsed. It happened in northeast Fort Worth off Riverbend Road.

A worker helping clear the collapsed wall debris died April 7 after being he was hit by an 18-wheeler. An OSHA statement Thursday said no violations were found or citations issued over the second fatal accident.

Construction of the activity center was completed over the summer.

(©2015 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)