A man laced the atmosphere of a Baltimore theatre with menace when he began shouting "Heil Hitler! Heil Trump!" during intermission of a classic play set in a Jewish village in czarist Russia.

The patron's pro-Nazi and pro-Trump outburst during a Wednesday night production of Fiddler on the Roof sent dozens of panicked people running for the exits at Baltimore's Hippodrome Theatre.

Rich Scherr, a technology and financial journalist who was one of over 1,000 theatregoers attending the Wednesday night performance, said a man seated in the balcony was behind the commotion.

Sick, sad world. A man stands at intermission of tonight’s performance of Fiddler in Baltimore and yells, “Heil Hitler,” along with pro-Trump references. <a href="https://t.co/slDcPwF7re">pic.twitter.com/slDcPwF7re</a> —@writerguyRich

Scherr described stunned audience members freezing in fear when the man began shouting minutes into the intermission.

"Everything just got really, really quiet. And then I heard this guy screaming: "Heil Hitler! Heil Trump!" he said in a Thursday phone interview.

Other patrons told him they also heard the man yell about "MAGA," U.S. President Donald Trump's "Make America Great Again" slogan.

A few dozen people started running for the exits, according to Scherr, while others began calling out for security. Scherr said he braced for the possibility of gun violence in the packed theatre.

"You don't want to think the worst, but I was preparing to react in case of gunfire," Scherr said.

In a police report made public Thursday evening, hours after the story made waves, police said the man told officers he was actually motivated to shout out salutes to Hitler and Trump because of his disdain for the president. Officers said the man, identified as Anthony Derlunas, 58, told them he'd been "drinking heavily throughout the night." Law enforcers found he was not a threat to public safety.

The theatre scare comes a few weeks after a gunman fatally shot 11 people inside a Pittsburgh synagogue. The suspect in that shooting, Robert Bowers, 46, expressed hatred of Jews during the rampage and later told police that "all these Jews need to die," authorities said. It also comes days after the FBI released a report showing a 17 per cent spike in U.S. hate crimes in 2017 — with a 37 per cent increase in anti-Semitic hate crimes.

In a tweet, Jonathan Greenblatt, the chief executive officer of the Anti-Defamation League, responded to a Baltimore Sun article about the incident, describing it as "yet another sign that these are not normal times."

'Everyone was shaken up'

After several minutes, the man was quietly escorted out of the Baltimore theatre by security and the show continued without incident after the intermission ended. But Scherr said he thinks "everyone was shaken up" in the audience for the remainder of the night.

The Baltimore police said officers responded to the Hippodrome at 9:40 p.m. ET, but no arrest was made and the man was allowed to leave on his own.

"Though reprehensible, the man's words are considered protected free speech because he did not directly threaten anyone," said Matt Jablow, a spokesman for the Baltimore Police Department.

Whatever the man's intentions, police will be posted at the Baltimore theatre for performances through Sunday.

The Hippodrome Theatre said such behaviour would not be tolerated. They said their security co-ordinated efforts with city police who met the man as he was escorted out of the building.

We do not tolerate behavior like we saw last night during intermission at “Fiddler.” Security handled the situation swiftly. Our venue has a proud tradition of providing shared experiences to people from all walks of life and we will continue that tradition. —@HippodromeBway

"Our venue has a proud tradition of providing shared experiences to people from all walks of life, right in the heart of this wonderfully diverse city, and we intend to continue that tradition in the spirit of bringing people together, not dividing them," the theatre said in a statement Thursday.

Fiddler on the Roof is a bittersweet musical revolving around a poor Orthodox Jewish milkman, his rebellious daughters and other community members of a village in czarist Russia, and their faith that is tested by progress and repression. Set in 1905, it's based on stories originally written in Yiddish by Sholom Aleichem.

The Fiddler production playing in Baltimore is a touring version of the recent Broadway revival of the musical classic. (Evan Agostini/Invision/Associated Press)

The original Broadway production in 1964 starred Zero Mostel and had an almost eight-year run, offering the world such enduring songs as Sunrise, Sunset, If I Were a Rich Man and Matchmaker, Matchmaker. It's long been a staple for schools and community theatre groups.

The Wednesday night incident was first reported by The Baltimore Sun.