Rep. Carlos Henriquez (UPDATED: Monday, July 9, 10:05 p.m.)— State Rep. Carlos Henriquez entered a plea of not guilty on Monday afternoon in a Roxbury courtroom on charges that he assaulted a young woman and held her against her will in the vehicle. Judge Kenneth Fiandaca ordered Henriquez to appear back in court on Sept. 27. The Fifth Suffolk lawmaker was also told to stay away from certain addresses in Somerville and Arlington, which are associated with the alleged victim.

The Democrat, who represents parts of Dorchester and Roxbury, was arrested early Sunday morning on domestic assault and kidnapping charges, according to the Boston Police Department. In a 364-word statement released on Monday night, he called the allegations "completely untrue."

Prosecutors said Monday that they believe the alleged assault happened in Arlington, not Boston, where Henriquez was arrested. Charges will be referred to Middlesex County for further action. Henriquez was represented on Monday by attorney Stephanie Soriano-Mills. He posted $1,000 bail on Sunday and has been released on his own recognizance.

Police allege that while driving around Boston with a woman, Henriquez got into a verbal altercation that escalated into a physical one, and Henriquez refused to let her out of the car. He was arrested at his home.

More coverage: What's ahead for the Fifth Suffolk district

According to the police report, the woman told officers "punched her with a closed fist repeatedly and strangled her while she was in his motor vehicle."

The report added that the woman, 23-year-old Katherine Gonzalves, said she attempted to jump out of the car and Henriquez sought to prevent her from doing so. Gonzalves, who told police she and Henriquez had been in an "intimate relationship about a month ago," jumped out of the moving car in the area of Forsyth St. and ran to Northeastern University police, the report said. "Both responding Boston Police Officers did observe scuffs on Ms. Gonzalves right shin and multiple bruises on her arms and wrists," the report said.

She also claimed he took her phone and SIM card and memory card, and that he had yelled at her in previous incidents.

According to the report, an officer asked Henriquez if he wanted to answer questions "or to explain his side of the story and he refused to do so."

The news of the arrest was first reported by WHDH. Rep. Henriquez, who was elected to the Fifth Suffolk District in the House in 2010, did not immediately return voicemails requesting comment.

"Currently, this matter is in the hands of the court and I am confident that when this process has run its course I will be vindicated of all charges," Henriquez said in a statement. "This matter will be tried in the court and not in the media or in the court of public opinion. I can assure my supporters and critics alike that I am innocent of these charges. I will follow the advice of my attorney and not provide any details of this incident, other than to say and reaffirm I am innocent."

Henriquez, 35, is up for reelection this year. While he does not face a challenger in the Democratic primary this September, Henriquez will likely face off against former state Rep. Althea Garrison. A perennial candidate, Garrison is expected to be on the Nov. 6 ballot as an independent.

The director of the right-of-center Massachusetts Fiscal Alliance, Paul Craney, said if the allegations are true, Democrats should start looking for another candidate in the Fifth Suffolk. “After reading Rep. Henriquez’s police report, I wouldn’t even want him to water my flowers," Craney said in an emailed statement. "If the allegations are true, he should immediately step down. This is a safe Democratic seat, the local Democratic party committee should start the process of looking to replace him. The Representative has the right to plead not guilty but the public also has a right to hear from their elected official. Henriquez should publicly explain why he is not guilty of these serious charges.”

But others held their fire, including Barry Lawton, who lost to Henriquez in the 2010 Democratic primary by 41 votes.

“I’m certainly not going to pre-judge him," Lawton said. "I just hope it was a big misunderstanding and it can be worked out. I can’t make any comment on it. It wouldn’t be fair or right.”

Garrison declined comment. "He has his own problems," she said.

State Rep. Marty Walsh, a Dorchester Democrat who chairs the House Ethics Committee, declined comment.

Henriquez spent the morning at Roxbury District Court, sitting in a conference room while waiting for his case to be called. On one side of the hallway, reporters and cameramen gathered, while supporters stood on the other. Supporters and interested parties included John Barros, head of the Dudley Street Neighborhood Initiative and a member of the Boston School Committee; local activist Jed Hresko; and Darnell Williams, CEO of the Urban League of Eastern Massachusetts.

"We just have to let the court sort it out," Williams said after the arraignment. "Anytime a public official takes a hit, it's a hit against all public officials."

Williams added: "I think it would be premature to jump in front of the court system."

Henriquez had a previous run-in with police, as a passenger in a car whose owner had an outstanding warrant and no front license plate on the vehicle. Henriquez took to Twitter to vent afterwards, questioning whether several police cars were needed for the stop.

(This story was updated on Monday, July 9 with information on Henriquez's court appearance and reaction to the appearance. It was later updated with the Henriquez statement.)

CORRECTION: Rep. Henriquez was arrested at his home. Due to incorrect information provided to the Reporter, the report initially said that he had been arrested on the scene at Forsyth St.