They called it the “death wagon.”

The dilapidated horse-drawn cart pulled onto a busy corner of Wall Street just before noon on June 16, 1920, and several people took note of it. They noticed innocuous details — such as the brown coat of the horse that pulled it — that only became important once the vehicle lay in countless splintered parts, destroyed by the 100 pounds of dynamite it was carrying. The intentional blast, one of the deadliest in the nation’s history, killed about 40 people and sent hundreds more to the hospital.

Rebecca Epstein, a stenographer for a brokerage firm, was returning from lunch when she saw the wagon. A red flag flew from the rear, which was open and hauling either boxes or barrels covered in a white powder, she told The Washington Post at the time. She said she saw the vehicle stop on the street in front of financial powerhouse J.P. Morgan and Co. and watched the driver walk away.

“I had reached the Equitable-Trust Building when the explosion occurred,” Epstein said. “I was knocked senseless, but I believe I would recognize the driver if I saw him. He was the laboring type, about 40 years old and was dressed in a suit of brown overalls.”

Lawrence Serbin, who had been selling chocolates nearby, recalled the driver as about 5-feet-6, unshaven and wiry. He remembered him speaking with a strong Scottish accent that Serbin heard when the driver directed him to move his own wagon.

“Pull your horse up, buddy,” Serbin recalled the man saying, according to a 1920 Post account. “When I pulled out of the way he went straight down Wall Street, and about a minute later I was knocked down and didn’t remember anything until I came to in the Broad Street Hospital.”

The bombing left the Financial District a battered scene of lifeless and broken bodies, and set off an intense, widespread investigation. Even so, the case was never solved. Although the event has been mostly forgotten with time, it is a reminder of how difficult bombing investigations can prove.

Authorities in Austin announced Monday that they are searching for a “serial bomber” whose latest use of a tripwire shows a “higher level of sophistication” than three earlier incidents that involved exploding packages. Then on Tuesday, a package thought to be headed for Austin exploded at a Texas FedEx facility, raising concerns that it was tied to the other bombings.

A $115,000 reward for information leading to an arrest and conviction is being offered.

“We need this to stop,” Christopher Combs, special agent in charge of the FBI’s San Antonio office, said Monday. “We are very concerned that people can get hurt just by walking now, when we have tripwires. A hundred thousand dollars is a lot of money, and we’re hoping somebody knows something, and that they can call us, and help us stop what is going on here.”

After the Wall Street bombing, a reward was also offered.

It began at $20,000 and, within a few months, rose to $70,000.

People at the time were angry, scared and wanted justice. Until the Oklahoma City bombing, it was the deadliest domestic terrorist incident in the country.

“Yesterday one of the greatest outrages ever committed against society was perpetrated on the very spot on which we stand,” Brigadier Gen. William Nicholson told a crowd that gathered in Wall Street the day after the explosion, according to the New York Times. “Are we, as American citizens, going to close our eyes to things like that? I say no, a thousand times no!”

“No!” the crowd shouted back.

“If a crime really has been committed it is the duty of every man here to take a solemn oath to do all he can to bring these vampires to justice,” Nicholson said. “No man who would take part in such a crime has any right in any community, not even in his own.”

The perpetrators were believed to be Italian anarchists, but news accounts show that various individuals drew scrutiny over the years for their potential roles. Immediately after the incident, suspicions centered on a man who had sent postcards warning of an explosion on Wall Street. That man, Edwin Fischer, a tennis champion, was later declared mentally unstable and committed to a hospital. News accounts at the time described him as walking with detectives while wearing three outfits at once: a wrinkled gray suit over a business suit over a tennis shirt and flannel pants, so he could be ready for a tennis match at any time.

The investigation also involved hundreds of officers canvassing stables and horseshoe establishments. The horse that had pulled the wagon was killed in the blast, but a major clue was found at its hoofs. Detectives found the shoes had recently been put on and bore letters used by union members.

Another clue was found two feet below the pavement, in a hole caused by the explosion. A man reportedly found three pieces of curved metal that were determined to be part of a bomb. They matched another piece of metal that was found in the body of a 16-year-old messenger who was killed. The teenager, Robert Westday, was employed by brokers and was hit in the abdomen by the metal, according to news reports.

Black and white photos capture the devastating scene that day: a car toppled on its side, oddly shaped pieces of fabric draped over bodies, chunks of metal shrapnel as thick as a child’s wrist.

The death toll started in the low 30s the first day and rose to 39. Among the dead was Catherine Dickinson. She had recently lost her father and brother and had taken an early lunch that day to help a friend, according to news reports. She was waiting on the corner for that friend when the explosion occurred. Also killed was William Joyce, a 24-year-old clerk at J.P. Morgan. His father, Thomas Joyce, who headed the company’s gold shipment department, was 25 feet away from him at the time and refused to go to the hospital for his own wounds because he wanted to stay with his son.

Estimates of the injured ranged from 200 to 300. One of them was Joseph Kennedy, father of future president John F. Kennedy. He was reportedly outside at the time and tossed to the ground by the detonation’s force.

But in a sign that not all the injuries were physical, a few days after the bombing, the death toll rose by one.

A married bank clerk with a 5-year-old son had survived the explosion but his nerves remained shattered by what he had witnessed, according to a New York Times report. When co-workers suggested he go home at 3 p.m., he walked instead to the roof of the bank and, as people walked along the sidewalk below, jumped 10 stories to his death.

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