Updated 07/04/14 – 10 p.m.

CHICAGO (CBS) — Crowds became so heavy at Navy Pier more than two hours before a July 4 fireworks show that officials had to close the entrances at the lakefront venue.

Officials closed the gates to new arrivals at 7 p.m., citing safety concerns. The 15-minute fireworks show was scheduled to begin at 9:30 p.m.

More than 100,000 people were on the pier.

“To ensure the safety and comfort of all our guests, no additional visitors will be allowed to enter Navy Pier,” organizers said in a news release.

Pier officials said anyone leaving Navy Pier would not be readmitted. They reminded the public there also will be fireworks Saturday night at 10:15 p.m.

The on-site parking garages were already full by 2:30 p.m., seven hours before the fireworks show.

CBS 2’s Vince Gerasole reports huge crowds were expected along the lakefront, thanks to picture perfect weather, which will make it a more challenging to stake out a spot the longer you wait to get there. City officials have advised people to get there Friday afternoon to make sure they get a good vantage point.

With the combination of a great forecast and Independence Day falling on a Friday this year, there’s the potential for much larger crowds than usual at Navy Pier for its July 4th fireworks show.

“You can really see them down the entire south dock at Navy Pier, but we encourage people to go as far east as possible, and to come as early as possible … as there’s always a chance that we collectively decide with the Police and Fire Departments that we might shut down the pier,” said Navy Pier entertainment director Jen Kramer.

Officials reminded visitors coolers, bikes, skateboards, rollerblades and skate shoes are not allowed on the pier itself. All bags also are subject to search for security reasons. Pets and animals are prohibited, except official service animals.

Kramer said this year’s fireworks show will have larger shells, which will fire up to 1,200 feet in the air. The shells come from all around the world, including China.

“Theirs are very, very bright; and very flashy; and very traditionally red in nature, and white,” she said.

Not long ago, as many as 1 million people flocked to Grant Park for the city’s more elaborate fireworks display on July 3rd. That fireworks show ran in conjunction with the Taste of Chicago, but for budgetary reasons, the city scrapped the July 3rd fireworks in 2010, opting for two smaller July 4th shows on the North Side and South Side, in addition to the Navy Pier display.

In 2011, the city scrapped the North Side and South Side fireworks shows, leaving only the Navy Pier fireworks show on July 4th.

On a typical summer day, about 60,000 people visit Navy Pier. That crowd is expected to double on Friday.

“There’s gonna be a lot of people down there. Take public transportation. Always be aware of your surroundings, as you should in any large crowd,” said Rich Guidice, managing deputy director of the city’s Office of Emergency Management and Communication.

The big crowds are welcome news for the businesses along the lakefront.

“Best weekend out of of the whole year. We expect thousands of people lining up over here for smoothies, and sausages, and hot dogs,” said Jacob Gasienica, an employee at Jucy Jay’s smoothie and juice bar at Monroe Harbor, just south of Navy Pier.

Mark Stern, co-owner of The Big Kahuna charter party boat, based in Monroe Harbor, said “This weekend is as big as it gets.”

Kramer said the Navy Pier fireworks have been so well-received, she’s considering the possibility of trying to host the International Pyrotechnics Competition, which would draw fireworks fans from around the world.