Emergency workers are seen in a parking garage not far from where a collapse occurred, killing one worker and trapping another at the Westfield Montgomery Mall on Thursday. (Matt McClain/The Washington Post)

Relatives of the construction worker killed when a 50,000-pound concrete slab collapsed at a mall parking garage in Montgomery County on Thursday are mourning the loss of their 57-year-old patriarch, who doled out nicknames to loved ones and had been a laborer for more than three decades.

But even as funeral plans were being made Friday for Carroll Dexter Wills of Prince Frederick in Calvert County, his family was left without answers about what went wrong at the garage at Westfield Montgomery mall in Bethesda.

A second worker who was with Wills was pinned for four hours as crews cut through concrete and steel to pull him to safety. That man, who has not been identified, remained in critical condition at Maryland Shock Trauma Center on Friday.

Montgomery police ruled the collapse an accident and ended their part of the probe, according to a department spokeswoman. The investigation of why the chunk of concrete fell now falls to the Maryland Occupational Safety and Health division, which would not comment Friday.

On Thursday, a company official called Wills’s 83-year-old mother, Yvonne Wills, to say that two men — including her son — had been trapped and that one of them had died, said Carroll Wills’s niece, Olivia Smith. He called again later to say it was her son who had died. Smith said that the head of the union Wills had been a member of for 30 years, Ironworkers Local #5, visited the family.

Wills “loved his job,” said Smith, who had been given the nickname “Little Barb,” after her mother. “He lived for that job. He wouldn’t be doing anything but that. He wasn’t a sit-down type of guy.”

Smith said her uncle, who called himself “Star Child” because he stood out wherever he went, began working construction after graduating from what is now Calvert High School. He was single and had three sons and a daughter. One son died in a car accident in 1997; the others are young adults.

“If you knew him, you loved him,” Smith said of Wills.

She said he didn’t talk about the details of his work or his latest job, other than to say it was at the mall. He had been employed part time, but Smith said he was expecting to hear any day if he could go full time.

Whiting-Turner, a construction company based in Baltimore County, is the project’s general contractor, county officials have said. It was not clear if that company or a subcontractor had been working on the part of the garage that collapsed.

Donna Bigler, a county government spokeswoman, said the project includes renovations and expansion of the mall’s food court, movie theater and adjacent parking garage. She said workers are busy looking at work permits to determine whether everything was in order, a process that wasn’t expected to be completed until at least Tuesday.

On Friday, the county issued a stop-work order, which will be in place until the investigation is completed, officials said.

A woman who answered the phone at Whiting-Turner said that company officials do not speak to the media.

On Friday, Wills’s family gathered at his mother’s house, telling old stories but haunted by the events of Thursday afternoon.

In the first call about the accident, Yvonne Wills was told that one of the people trapped was still alive, offering some hope to relatives. “We knew he was a fighter, a strong person,” Smith said. “But it didn’t take long for the official to call back and say, ‘Sorry, Ms. Wills. He passed.’ ”

Jennifer Jenkins contributed to this report.