Agents from the FBI use binoculars from the broken window where a gunman opened fire at the Mandalay Bay hotel, Wednesday, Oct. 4, 2017, in Las Vegas.

:: Investigators believe a note found in the Las Vegas gunman’s hotel room contained a series of numbers that helped him calculate more precise shots, a law enforcement official said.

Vice President Mike Pence appeared at a prayer service in Las Vegas on Saturday to mourn the victims of last weekend’s concert shooting and to praise those who risked their lives to save others.

Federal officials also began hauling away thousands of personal items left behind in the concert venue after Stephen Paddock unleashed a fury of gunfire from his Mandalay Bay hotel room, killing 58 people and injuring nearly 500.

More about the deadliest mass shooting in modern US history:

The investigation

A law enforcement official told The Associated Press on Saturday that the numbers found on a note located on a nightstand included the distance between the high-rise hotel room that Paddock was using as a perch and the concert below.

The official wasn’t authorized to discuss the details of the ongoing investigation publicly and spoke on condition of anonymity.

Investigators are still working to determine why Paddock committed the deadliest mass shooting in modern US history.

On Friday, FBI agents announced plans to put up billboards throughout Las Vegas to ask people with credible information to call with tips. The number is 800-CALL-FBI.

Forever etched in hearts

Vice President Mike Pence told mourners at a prayer service in Las Vegas that the memory of the victims of last weekend’s shooting massacre will “forever be etched into the hearts of the American people.”

The vice president traveled to Vegas on Saturday to attend a ceremony honoring the 58 victims. He says amid the depths of horror, Americans have found hope in those who risked their lives to help save others after the shooting.

After he spoke, 58 doves were released on the steps of City Hall to commemorate each victim. Someone shouted, “God bless America!” as the doves disappeared into the distance.

‘He is my hero’

One of the first memorials services for victims of the Las Vegas shooting massacre was held Saturday in Bakersfield, California, for Jack Beaton , who died shielding his wife from gunfire.

His wife, Laurie, recalled that he yelled at her to get on the ground, put his body on top of hers for protection and told her he love her before going limp.

“I knew every day that he would protect me and take care of me and love me unconditionally, and what he did is no surprise to me,” she said. “He is my hero.”

Jack Beaton was remembered as a fun-loving friend, a hard-working roofer by trade, a generous and kind-hearted neighbor, and, above all, a devoted husband and father to two children.

‘Our people, they didn’t run’

Members of a private security firm that manned last weekend’s concert and stayed in the venue to help other people flee are starting to return to work .

“Our people, they didn’t run,” said supervisor Cheryl Metzler.

The Las Vegas branch of Contemporary Services Corporation lifted concertgoers over barriers and hid them behind pillars as gunfire rang out from the 32nd floor of the Mandalay Bay hotel casino. Many are traumatized and mourning the loss of a co-worker, 21-year-old Erick Silva, who was among the 58 people killed. Two other guards were wounded.

Darla Christensen was checking concertgoers’ bags and boots for alcohol and contraband and inspecting wristbands when gunfire erupted. She grabbed other guards and patrons and pushed them toward a side gate.

On Friday, she put on her uniform to work a UFC weigh-in, her first event since the shooting. “Even just going, even just getting dressed, was hard,” she said. “It was really tough.”