One of the Texas lawmakers involved in an argument on the House floor Monday says he has been receiving threats.

"I have been in contact with DPS, and I have let them know that I want to have my house monitored, that I want to have our district office monitored. They have been very quick to respond," said State Rep. Ramon Romero, D-Fort Worth.

Hundreds of protesters opposing Texas' tough new anti-"sanctuary cities" law launched a raucous demonstration from the public gallery in the Texas House on Monday, briefly halting work and prompting lawmakers on the floor below to scuffle.

The argument began after hundreds of protesters opposing Texas' tough new anti-"sanctuary cities" law launched a raucous demonstration from the public gallery in the Texas House on Monday, briefly halting work and prompting lawmakers on the floor below to scuffle -- and even threaten gun violence -- as tense divides over hardline immigration policies boiled over.

Activists wearing red T-shirts reading "Lucha," or "Fight," quietly filled hundreds of gallery seats as proceedings began. After about 40 minutes, they began to cheer, drowning out the lawmakers below. Protesters also blew whistles and chanted: "Here to stay!" and "Hey, hey, ho, ho, SB4 has got to go," referring to the bill that Gov. Greg Abbott signed into law this month.

Hundreds of protesters opposing Texas' tough new anti-"sanctuary cities" law drowned out lawmakers in the Texas Capitol on the final day of the legislative session, Monday, May 29, 2017.

Some unfurled banners reading: "See you in court!" and "See you at the polls!"

State House leadership stopped the session and asked state troopers to clear the gallery. The demonstration continued for about 20 minutes as officers led people out of the chamber peacefully in small groups. There were no reports of arrests.

Texas' new law is reminiscent of a 2010 Arizona "show your papers" measure that allowed police to inquire about a person's immigration status during routine interactions such as traffic stops. It was eventually struck down in court.

A legislative session that began in January concluded Monday, and the day was supposed to be reserved for goofy group photos and sappy goodbyes. Lawmakers are constitutionally barred from approving most legislation on the last day.

But even after the protest ended, tensions remained high. Romero said he was standing with fellow Democratic Rep. Cesar Blanco of El Paso when Republican colleague Matt Rinaldi came over and said: "This is BS. That's why I called ICE."

A statement regarding today. pic.twitter.com/M0BcBXa43P — Matt Rinaldi (@MattRinaldiTX) May 29, 2017

Rinaldi, of Irving in suburban Dallas, and Blanco then began shouting at each other. A scuffle nearly ensued before other lawmakers separated the two.

Later, a group of Democratic lawmakers held a press conference to accuse Rinaldi of threatening to "put a bullet in the head" of someone on the House floor during a second near scuffle. They said the comment was made in the direction of Democratic Rep. Poncho Nevarez, from the border town of Eagle Pass.

In a subsequent Facebook statement, Rinaldi admitted saying he'd called federal authorities and threatened to shoot Nevarez -- but said his life was in danger, not the other way around.

"Nevarez threatened my life on the House floor after I called ICE on several illegal immigrants who held signs in the gallery which said 'I am illegal and here to stay,'" Rinaldi wrote. He said Democrats were encouraging protesters to ignore police instructions and, "When I told the Democrats I called ICE, Representative Ramon Romero physically assaulted me, and other Democrats were held back by colleagues."

Hundreds of protesters opposing Texas' tough new anti-"sanctuary cities" law launched a raucous demonstration from the public gallery in the Texas House on Monday, briefly halting work and prompting lawmakers on the floor below to scuffle.

Rinaldi said Nevarez later "told me that he would 'get me on the way to my car.'" Rinaldi said he responded by making it clear "I would shoot him in self-defense," adding that he is currently under Texas Department of Public Safety protection.

NBC 5 has reached out to Rinaldi several times, and we have not heard back.

Republican State Rep. Rodney Anderson, who also represents part of Irving, was on the floor when the argument happened. He knows all of the lawmakers involved.

"You had some passionate people on both sides. Nerves are frayed, and it is one of those situations that is unfortunate, because it reflects poorly on the body, and it does not do anything to advance legislation to help the people of Texas," Anderson said.

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At their news conference Monday, Democratic lawmakers vowed to target Rinaldi's seat. His district is a competitive one. Rinaldi won by fewer than 1,200 votes.

"Dallas County is a very competitive county, and I would be more surprised if there was not a challenger for any of the Dallas County Republicans," Anderson said.

The Associated Press' Meredith Hoffman and Will Weissert contributed to this report.

