Charlottesville Police Chief Al S. Thomas Jr., shown on Saturday, said Monday that his force had to adjust quickly as circumstances changed at the rally. (Win Mcnamee/Getty Images)

The Charlottesville police chief defended his department’s response to the mayhem triggered by a white-nationalist rally in the Virginia city this weekend, responding to criticism that his officers did not do enough to prevent the bloodshed.

Police Chief Al S. Thomas Jr. said he regretted the loss of life after the violence ended in the death of a Charlottesville woman hit by a driver accused of ramming into counterprotesters, and the deaths of two Virginia state troopers killed when the helicopter they were in monitoring the rally crashed.

Thomas said organizers of the Unite the Right rally did not follow what the chief said had been an agreed-upon plan that involved controlling the demonstrators’ access to Emancipation Park through a rear entrance.

When rally attendees started coming in from all sides Saturday morning, the chief said, his officers had to alter their plans and transition into protective gear from the street uniforms they were wearing. Protesters and counterprotesters converged in some pitched battles in the streets before Charlottesville police, backed by Virginia State Police, quelled the fighting.

Thomas said his force was never too far from the melee and had a “very large footprint,” intervening in street fights and evacuating the park.

“Charlottesville police officers were originally on-site in their everyday uniforms,” he said during a Monday afternoon news conference. “We again were hoping that the members of the alt-right rally would cooperate with our safety plan of ingress and egress.”

The Charlottesville Police Department has been pummeled by intense criticism since the calamity Saturday, with all sides accusing officers of reacting too slowly to the chaos in streets around the park and standing idly by as clashes erupted.

Thomas dismissed reports that officers were discouraged from making arrests. “That is simply not true,” he said.

The heavily armed demonstrators from the alt-right rally at the park and counterprotesters spilled into the streets by 11 a.m., throwing punches, beating one another with sticks, spraying chemical agents and drawing blood throughout downtown Charlottesville, as police tried to keep the groups separate, they said.

By then, city officials had declared the rally an unlawful assembly and the governor declared a state of emergency.

Thomas denied that his officers were intimidated by the firepower of the protesters, including the presence of militia with military-style semiautomatic rifles, but said it was prudent for them to change into riot gear before returning to confront the violence. After clearing the park, it took police about an hour to regain control of the streets, and officers begin following different groups of “mutually combative” troublemakers but did not specify who Thomas thought was ultimately responsible for initiating the violence.

“It was a challenge,” he said. “We were spread thin once the groups dispersed.”

Thomas said more than 250 calls for service came in, including from people injured when a driver rammed into a crowd of antiracism protesters on 4th Street, killing Heather Heyer, 32, and sending 19 others to the hospital.

James Alex Fields Jr., 20, of Ohio was denied bond Monday and is being held at the Albemarle-Charlottesville Regional Jail on multiple felony charges, including second-degree murder, in the incident in which police allege he drove his Dodge Challenger through the crowd and fled the scene before his capture.

The police chief said the department’s “action plan” called for the street crossing where Heyer was killed to be closed but it was less clear why it may have been open at the time Fields is accused of driving into the crowd at a high speed after a collision with another vehicle.

Asked whether he had regrets, Thomas said: “Absolutely. . . . It was a tragic, tragic weekend.” But when pressed by a reporter about whether his police officers were adequately prepared, the chief reiterated that his specific regret was the tragic outcome of the day.