Editor's note: This story has been updated to include links to the related investigation and to reflect the incident occurred in the evening.

A pickup pulling a horse trailer drove through a crowd of Black Lives Matter protesters on a Tulsa interstate Sunday evening, sending two people to the hospital with what a law enforcement spokeswoman described as “minor injuries.”

The incident occurred on Interstate 244 eastbound near Detroit Avenue. The driver wasn't initially stopped by law enforcement at the scene; but an Oklahoma Highway Patrol spokeswoman said troopers later stopped the truck and were questioning the driver.

One of the organizers of the Black Lives Matter rally, the Rev. Eric Gill of Metropolitan Baptist Church, said a red truck being driven by a man "who put a gun on the dashboard and threatened us before he took off" was in the vehicle that drove through the crowd.

The man wasn't initially detained by law enforcement after the incident.

"The fact that they let him go is a microcosm of what we have been going through," Gill said.

A video of the scene posted on Tulsa television station Fox-23's Facebook page shows the truck driving through the crowd and then stopping near a group of state troopers. Protesters can be seen running toward the truck before it pulls away.

OHP spokeswoman Sarah Stewart said troopers met the driver at a different location for an interview to get him away from the “agitated” protesters. At least two people were injured when he drove through protesters.

Stewart said Sunday night the incident remained under investigation.

Tulsa World photographer Mike Simons was at the scene documenting the rally when the truck drove through the crowd.

The crowd let a car driven by a black female pass through and the pickup attempted to follow the car. Protesters blocked the driver’s path, and the man then placed a handgun on his dashboard, Simons said. That angered protesters, who began throwing water bottles at the vehicle.

The driver then accelerated through the crowd, said Simons, who was standing near the vehicle when it happened.

“It was fast enough that I felt like I had to run,” Simons said. “Everybody felt like they had to run. People scattered.”

In addition to at least two who were taken to the hospital, others were hurt, Simons said. A woman was lying on the ground, and people quickly tried to assist her as they were shouting for medical help.

Gill said he was standing right next to the vehicle when it started moving through the crowd.

“We let the silver car in front of them go because she had an emergency she had to get to, so we let her go,” Gill said. “He took the liberty to continue going as bystanders stood in front of him.

“He stopped, and then as he inched in front of people and kept bumping people, the people got upset and hit his car. But then he put his gun on the dashboard of his car and told everyone, ‘You get out of my way.’

“And then he proceeded to drive through people and hit people.”

Gill said he did not believe it was anything the protesters did that caused the man to continue driving.

“It was him,” Gill said. “He decided and made an intentional effort to drive through us.”

(Related story: The Oklahoma Highway Patrol was investigating Monday.)

(Related story: Law enforcement officials say investigation continues)

Protest organizers urged people to leave the interstate, and the crowd soon moved back into downtown Tulsa before gathering at the jail.

Protesters held a rally in the Greenwood District before marching south and onto I-244.

The interstate was reopened Sunday evening after being closed for about two hours.

Several hundred people attended the event that began at 5 p.m. Sunday, where several speakers addressed the crowd.

Participants chanted "No Justice, no peace, no racist police," "Black lives matter" and "Hands up, don't shoot."

Sunday's event followed a similar protest on Saturday in which more than 1,000 people converged on Peoria Avenue in the Brookside District. The group eventually walked to Interstate 44 and shut down the highway for part of the afternoon before returning to Brookside. 

Sunday's event in Tulsa also follows a video event held earlier in the afternoon by the Tulsa Race Massacre Centennial Commission to commemorate the 99th anniversary of the Tulsa Race Massacre.

Demonstrations across the U.S. took place Saturday after Officer Derek Chauvin, 44, was charged with third-degree murder and second-degree manslaughter in the death of George Floyd death in Minneapolis. Chauvin also was accused of ignoring another officer who expressed concerns about Floyd as he lay handcuffed on the ground, pleading that he could not breathe as Chauvin pressed his knee into his neck for several minutes. Floyd, who was black, had been arrested on suspicion of using a counterfeit bill at a store.

Gallery: Thousands rally, Several injured as a truck drives through Black Lives Matter protest