Investigators collect information from the scene at the intersection of Massachusetts Avenue, North Capitol and F streets following a pedestrian accident on Wednesday. (Nikki Kahn/The Washington Post)

Some people remember only the sounds of the crash — an engine revving, a traffic pole knocked over, people screaming. Others are haunted by the images — a black Ford Explorer racing south on North Capitol Street near Union Station, striking three pedestrians and pinning one under a catering van making a breakfast delivery.

“The car shot across the intersection so fast it was frightening,” said Judy Kuhn, who saw Wednesday morning’s accident while waiting for a bus along Massachusetts Avenue, near its expansive crossing at North Capitol Street.

In all, six people were injured, including two pedestrians whom police described as having life-threatening injuries. Also hurt were two occupants of the van and the driver of the SUV. No charges had been filed by Wednesday afternoon.

The accident occurred a few minutes before 8 a.m. outside the District’s busy transit hub, a time of day when thousands of commuters, tourists and residents cross paths. It closed vital roads near the station for more than seven hours, causing tie-ups and delays into mid-afternoon.

Witnesses said that two women who were hit had been standing on a median waiting to step into a crosswalk and that the woman who was pinned was crossing a small street that feeds into the intersection, described by residents as complicated and confusing for drivers and pedestrians. D.C. police did not release information on the pedestrians other than to describe them as adult women.

Trevelle Blount, who was driving the W. Millar & Co. catering van, said the woman trapped under his van was carrying a suitcase and had her back to the SUV when she was hit. Blount, who suffered a slight shoulder injury, said he talked to the woman’s brother at the hospital, who told him that she is a tourist from Colombia.

The crash scene was a debris field, with metal parts of vehicles strewed about along with clothing paramedics cut from the victims. The traffic signal, sheared at the bottom, was atop the roof of the SUV, its bolts dangling from a bottom plate. Small piles of clothing, some folded, most in disarray, were on the pavement. The general manager of the catering company, Karen Roosa, said a broken suitcase was found underneath the van.

Pedestrian accidents in the District have been on the rise this year. This year’s pace of those involving fatalities is on track to exceed the number posted in both 2012 and 2011.

D.C. police said eight people died in all of 2012 after being hit by vehicles, while seven people have already died in the first half of this year. In all of 2011, 11 pedestrian fatalities were recorded, according to police.

Several of this year’s crashes have been quite severe. The victims include a 71-year-old woman and longtime cafeteria worker at Sidwell Friends school who was struck as she stepped off a curb after a church meeting and a 92-year-old woman active in the city’s Muslim community who was hit as she crossed a street near her apartment. Both women died.

D.C. police said that the cause of Wednesday’s accident remains under investigation and that precise details were not available. But authorities confirmed accounts from several witnesses that the driver of the Explorer was headed south on North Capitol Street.

Some witnesses said the driver either went through a red light or was trying to beat it. Kuhn said the driver may have been stopped at the light and then raced forward. “The light was starting to change, and I heard the SUV’s engine rev up,” she said. “Then the car shot out across the intersection.”

Witnesses said the SUV crossed six lanes of Massachusetts Avenue and veered onto a median, striking a garbage can and the traffic signal before hitting the two women. The witnesses said the SUV then hit a third woman crossing narrow F Street, on the other side of the median, then slammed into the driver’s side of the catering van.

Blount saw the SUV speeding at him, but it happened too quickly for him to jump out of the van. “I saw people scattering, and as I turned, the car had already hopped the curb, ran over the pole and hit two people.”

“It hit them hard,” said Blount, 25, who has worked for the caterer for just two months. “Then there was the lady in front of me, in a skirt. It hit her in the back.”

All day, busy workers with suitcases and meandering tourists with luggage or maps walked by the crime scene tape and stared at the wreckage in front of the National Postal Museum and the Phoenix Park Hotel (workers there said none of the victims were guests).

Hotel bellman Jerry Agenar said the SUV appeared to be speeding as it came toward him, crashing into the van just 50 feet from his post under the hotel awning. A minister, Tyrone Warner, who also drives a limousine, said he went over to the victims to pray. And Billie Warren, a retired nurse, said she rushed to each of the women in the street.

She moved so fast that she left her purse next to one of the victims, and when she was finally forced out of the area by police, her abandoned bag had become part of the crime scene, photographed and logged as evidence. She had to wait two hours to get it back.

“It was chaos,” said Warren, 48, who was standing near the Postal Museum when the crash happened. “I ran to each to help, but I could not help.”

Nicole Chavez and Paul Kane contributed to this report.