Ugly Scenes at Nevada Convention Spark Concern Among DNC Officials

— -- Democratic National Committee Chair Debbie Wasserman Schultz raised concerns today about the party's upcoming convention in Philadelphia following an ugly showing by some of Bernie Sanders' supporters at the Nevada Democratic state convention in Las Vegas this past Saturday.

Footage from the Nevada Democratic state convention shows some Sanders supporters protesting after the credentials committee declined to seat 58 of their delegates. Video posted online shows some supporters shouting “Bernie or bust,” cursing Democratic Party Chairwoman Roberta Lange, and booing California Sen. Barbara Boxer when she came on stage to give a speech in support of Clinton.

The actions prompted Nevada Democratic Party leadership to send a formal complaint to the DNC.

“We believe, unfortunately, that the tactics and behavior on display here in Nevada are harbingers of things to come as Democrats gather in Philadelphia in July for our National Convention,” Bradley Schrager, general counsel for the Nevada State Democratic Party, wrote to the DNC Monday.

In a statement today, Wasserman Schultz said she found the details in the letter from the Nevada Democrats "troubling," and would be reaching out to both campaigns to have them denounce what happened.

No arrests were made at the convention, according to the Las Vegas police. Four officers were already on the scene for the convention, and between 10 and 15 additional officers were added as it went on.

The party's headquarters in Las Vegas were vandalized by some Sanders supporters Sunday after the convention, the Nevada Democrats said, and the headquarters were closed Monday amid security concerns. Since the convention, state party Chairwoman Lange has been harassed with threatening messages and phone calls, including death threats, and has had to be equipped with a security detail, police said.

“You should resign, you should be ashamed of yourself. You’re not a Democrat, you’re a fascist,” one caller said on an audio recording of a voicemail to Lange, which was obtained by ABC News.

“Congratulations on your election rigging scam. I just changed my party affiliation. You are the final reason for me to leave the Democratic party,” reads a text message also obtained by ABC News.

Las Vegas police said the graffiti incident is still under investigation.

Although Sanders has condemned violence and harassment, he has not issued an apology for the actions of some of his supporters. At a press avail in San Juan, Puerto Rico, Sanders did not respond to a reporter who asked for his reaction to the situation. He subsequently released a statement dismissing party leaders’ accusations that his supporters have a penchant for violence as “nonsense, ” and accused party leaders of preventing “a fair and transparent process from taking place.”

“The Democratic Party has a choice,” Sanders said in his statement. “It can open its doors and welcome into the party people who are prepared to fight for real economic and social change -- people who are willing to take on Wall Street, corporate greed and a fossil fuel industry which is destroying this planet. Or the party can choose to maintain its status quo, remain dependent on big-money campaign contributions and be a party with limited participation and limited energy.”

In his statement, Sanders also noted that shots were fired into his campaign office months ago, and one of his campaign staffers had his apartment broken into and ransacked.

Senate Majority Leader Harry Reid, who has urged Sanders to condemn the violence, said he was disappointed with Sanders’ response.

“Bernie is better than that,” he said. “I’m surprised at the statement. I thought he was going to do something different.”

The Nevada Democrats released a statement today saying Sanders' response was inadequate.

Clinton won the Nevada caucuses when they were held in February. By ABC News' count, she currently has a lead of five pledged delegates. Once the votes have been counted, however, the delegates have to actually get selected, first at county conventions and then at the state convention. Due to events at the county conventions, the Sanders campaign ended up heading into the state convention with more delegates than Clinton. However, according to the Nevada Democrats, Clinton ended up filling 98 percent of her delegate slots, and Sanders only filled 78 percent, giving her a larger delegate count.

The Sanders campaign said that there were 64 delegates who were not allowed to be seated at the convention, claims the Nevada Democrats have pushed back on. In a post on Medium, the organization explained that six of those 64 delegates were seated and the others were not because they had purportedly not complied with the rules and registered with the Democratic Party by May 1, and/or the party could find their information.

“Everything the State Party did here was fair, transparent and appropriate according to our delegate selection plan,” the Nevada Democrats wrote in the post on Medium. “The convention rules were consistent with how previous State Conventions have been run in previous election cycles.”

ABC News’ Shushannah Walshe, MaryAlice Parks and Ali Weinberg contributed reporting.