(Reuters) - Protesters for and against Trump faced off in a plaza a few blocks from the site of the Republican National Convention in downtown Cleveland on Monday, shouting slogans at each other but avoiding physical confrontation.  Dozens of protesters were separated by a wall of police that looked equal in number.  To one side of the police line at the foot of the Key Tower, Cleveland’s tallest building, demonstrators shouted, “Black Lives Matter.” From the other side came, “You’re a bunch of anarchists.” The exchanges marked the first emotionally charged demonstration at the 2016 Republican National Convention, where security forces are on alert for potentially disruptive conflicts.  A combination of intense rhetoric by presumptive Republican candidate Donald J. Trump, recent police shootings of African- Americans in Baton Rouge and the Minneapolis area, and the killings of police in Dallas and Baton Rouge has raised tensions in the run-up to the convention.  Alicia Street, 31, a Black Lives Matter activist from Ferguson, Missouri, told Reuters that police appeared to outnumber the protesters. “We don’t need all these police. This is just free speech,” Street said shortly after a group of pro-Trump protesters left the area. “They are going to make people afraid.” Smaller demonstrations were held elsewhere in the downtown area. At least two protesters were seen carrying firearms. A  group of people identifying themselves as “anti-gay Christians” shouted at a rival group. One person carried a sign that read, “Stop being a sinner and obey Jesus.” A speaker at an anti-Trump rally was arrested, but police said it was unrelated to the campaign. One protest leader, Kait McIntyre, 27, said organizers from her group had sought permission for weeks to march outside the protest zone and only recently received it from the city.  “We wanted to get within sight and sound of the actual convention. We wanted our voices heard,” she said. 