(AP) -- Two days out from the official start of the Republican National Convention, security in downtown Cleveland appeared ready Saturday with heavy metal barriers blocking streets as officials and residents hoped that a peaceful and successful convention would further burnish the Cleveland's reputation as a city on the rise.

Vehicle and pedestrian traffic began to thicken Saturday afternoon along one of the city's main thoroughfares. Small children splashed happily in water jets at the refurbished Public Square nearby, which officials view as the city's commons.

Traversing downtown became a challenge with barricades staffed by Ohio National Guard members blocking or restricting traffic on streets surrounding police headquarters and the Cleveland Convention Center, where many of the 15,000 credentialed media in town will work. A hardened security perimeter under control of the U.S. Secret Service around the convention venue, Quicken Loans Arena, also was in place.

What will happen outside the convention hall starting Monday, the first day of the four-day convention, is uncertain. Cleveland's mayor and police chief have repeatedly said the city is prepared for all kinds of situations, but as other cities in the U.S. and abroad have tragically experienced in recent days and weeks, it's impossible to foresee everything.

The U.S. Homeland Security secretary told a congressional panel on Thursday that he expects violent clashes in Cleveland during the convention. The threat of terrorism hangs over every large event like a convention, but in this election cycle, the presumptive Republican presidential nominee, Donald Trump and his inflammatory rhetoric has added additional layers of concern about unrest and violence.

Downtown Cleveland had a different feel on Saturday beyond the barriers. Police officers traveled streets wedged inside all-terrain vehicles. Laws enforcement and military-type helicopters buzzed and hovered in restricted airspace downtown.

Earlier in the day a group of police officers on bicycles pedaled by a small rally connected to this weekend's Convention of the Oppressed. Members of the New Black Panther Party spoke at the rally and provided security. None carried weapons at the rally, which the group's national leader said would occur in Cleveland.

Ohio is an open carry state where the law allows legal gun owners to carry firearms in public. A Black Panther who identified himself by the single name of Herukhuti provided a cryptic response when asked about the open carry of firearms, saying, "When it happens, it happens."

"We are prepared to arm if necessary," Herukhuti said.

Chuck Allen sat on his bicycle Saturday afternoon watching the activity on Public Square. He had driven in his car from a western suburb to the west side and then biked across the Cuyahoga River into downtown.

Allen said he hoped that Cleveland's convention experience would be similar to the Cleveland Cavaliers victory parade after winning the NBA championship. An estimated 1 million people poured into downtown to celebrate the championship with few reported problems. Allen thinks the turmoil that has followed Trump throughout the campaign could mean clashes between his supporters and detractors.

"People living in Cleveland are afraid to come downtown because of the protests," Allen said.

Mordecai Cargill, 25, earlier this year joined the thousands of millennials who have made downtown Cleveland their home, a key ingredient to the city's renaissance. He's heard the "doomsday scenarios," but is hopeful the city will remain calm in the next week.

"I'm putting faith in the city that leaders are prepared," Cargill said.