The first act of Fiddler on the Roof, one of the most popular American musicals, which is performed frequently across the country, had just ended at the Hippodrome Theatre in Baltimore on Wednesday night. The Russians had staged a pogrom against the Jewish residents of a village – an organised act of ethnic persecution – storming a wedding celebration.

Connor Drew and his girlfriend had just stepped into the lobby after the house lights went up when he heard a disturbance in the upper balcony.

There was shouting. In a display that shocked audience members, a man stood up and yelled “Heil Hitler, Heil Trump” repeatedly during the intermission, according to several witnesses. It was the latest in a recent string of antisemitic incidents in the United States. Mr Drew said the man appeared to be in his late 60s or early 70s, had white hair and was wearing a hat and a raincoat. He was escorted out minutes later.

“Everyone was whispering and consoling everyone because a lot of people were really startled,” Mr Drew said. A woman sitting nearby was on her phone expressing fear there was about to be another mass shooting, he added. “I wasn’t afraid of violence. I was just more afraid of the situation in general and seeing how people were shaken by it.”

Beth Pendergast attended the touring production with her 23-year-old daughter. She was sitting near the man in the balcony when he started to yell and said the incident was “frightening and disturbing.”

“I’m like shrinking in my seat thinking, ‘Oh my God, does this guy have a gun?'” Ms Pendergast said.

Matthew Jablow, a spokesperson for the Baltimore Police Department, said the man had been identified but no charges would be filed.

“As reprehensible as the man’s words were, they are considered protected free speech because nobody was directly threatened,” Mr Jablow said. The show went on after intermission.

The original Fiddler on the Roof, which debuted on Broadway in 1964, tells the story of a milkman, Tevye, seeking to maintain his family’s religious traditions at a time of rising antisemitism. A popular Yiddish-language version of the show, put on by the National Yiddish Theater Folksbiene, is running at the Museum of Jewish Heritage in lower Manhattan, in New York City, through 30 December. It will transfer to Stage 42 in midtown Manhattan, where previews will begin 11 February.

The Baltimore incident comes as the nation is mourning the deaths of 11 people killed in October at a Pittsburgh synagogue, among the deadliest attacks on a Jewish group in US history.

Antisemitic incidents have been on the rise in the United States. According to a report released by the Anti-Defamation League early this year, they jumped almost 60 per cent in 2017 compared with the previous year. Much of the increase involved events that occurred in schools or on college campuses.

The National Yiddish Theater Folksbiene said in a statement that “antisemitic outbursts during the Baltimore production of Fiddler, precisely after a scene of a pogrom, shows how antisemitism is unfortunately still alive and well in 2018.”

“The cast and company of the Yiddish Fiddler is still reeling from the Pittsburgh massacre," the statement also said.

Rich Scherr, a contributing sports writer for The Baltimore Sun, was at the Hippodrome, in the orchestra section. He posted a video on Facebook of the tense aftermath, in which audience members can be heard yelling, “Get out!” It was unmistakable what the man was yelling, Mr Scherr said.

“I was waiting to hear a gunshot, frankly,” Mr Scherr said, adding that several members of the audience began to run for the exits. Security escorted the man out, according to Mr Scherr, “with no commotion.”

The whole incident lasted about five minutes and a spokesperson for the Hippodrome said the man was now banned from the theatre. As of early Thursday afternoon, police had not released his name.

The Hippodrome issued a statement describing how its security team, along with the ushers, was able to remove the man from the theatre. It also apologised to patrons via Twitter.

A spokesperson for the Hippodrome said staffing would be increased for the remainder of the show’s run, through 18 November, after which it heads to Pittsburgh.