JARRELL, Texas (KXAN) — The Jarrell Fire Department said Wednesday it took 16 hours using heavy machinery overnight to recover two men who died in a trench collapse Tuesday.

The incident took place at a construction site near the Interstate 35 frontage road around exit 275. Jarrell Fire Chief Officer Mark McAdams said in an update Wednesday the collapse occurred just before 8:30 a.m. Tuesday. The men, who were working in the trench for a sewer line, were buried over 20 feet deep in a space that was only two feet wide.

The victims’ names were not released Wednesday.

McAdams said when crews arrived, they discovered more crews and machinery were needed to safely rescue the workers. But two hours after the collapse, the men were presumed to be dead, because of how much soil buried them.

The machinery was used to make a “stairstep” down to the level of the victims and create a safe pathway for first responders, McAdams explained. He called the process “complicated” because of the depth of the trench and the soil.

The first person was found at 4:10 a.m. and recovered at 6:18 a.m. The second worker was recovered at 7:24 a.m., according to McAdams. In all, the operation took 23 hours.

Jarrell officials thanked first responders who came from all over Williamson County and the Austin area to help dig out the men.

“I couldn’t be more proud of the responses of all of the units within the Williamson County area to quickly respond and to treat this tragedy with the respect and with the quality of emotion and content that they did,” Jarrell Mayor Larry Bush said.

Bush said Williamson County Victim Services is helping the workers’ families. The men were graduates of the Jarrell Independent School District, and some of their family members worked for the district.

Superintendent Toni M. Hicks said the district is helping to support the victims’ families.

The cause of the collapse is being investigated by the Williamson County Sheriff’s Office and the Occupational Safety and Health Administration.