INDIANAPOLIS (NewsNation) — After two years of COVID-19 restrictions, Sunday’s 106th running of the Indianapolis 500 is expected to be one of the most attended races of the past 20 years, according to officials.

“We are under 10,000 tickets remaining inside our grandstands,” said Indianapolis Motor Speedway President Doug Boles.

A crowd of more than 300,000 is expected to descend at “The Greatest Spectacle in Racing.”

Seats have been completely sold out in the following sections: Pit Row terrace, Tower terrace, H stand, J stand, the A, B, E, and Paddock penthouses.

“The one area where we have the most tickets remaining is the North Vista,” said Boles. That’s the area between Turns 3 and 4. Boles estimates about 6,000 and 7,000 seats are left in that section.

According to Boles, Sunday’s race will be the most attended Indy 500 since the 100th running in 2016.

“With the expected crowd, it’s important for fans to arrive as early as possible with plenty of time to park and patiently make their way in through the gates. The earlier you can arrive, the better. There’s no shortage of things to do at the track, even several hours before the green flag. I hope everyone will treat this like the 100th running and come out in the early morning hours ready for an epic day.”

After the mass shootings at a Uvalde, Texas, elementary school and a Buffalo, New York, supermarket, Indianapolis 500 officials said on Thursday there was a high level of concern surrounding this year’s race.

“The level of concern is high,” Boles said. “It always has been since 2013, when the Boston (Marathon) bombing happened, and it caused us to completely rethink the ways we bring customers into the facility.”

More than 1,100 law enforcement officers will be on duty on race day, including undercover, plainclothes and uniformed police.

Boles said preparations have included planning for everything from an active shooter to bombs, but Indianapolis Motor Speedway has not asked for additional resources following the shootings.

Race fans coming “Back Home Again in Indiana” are encouraged to plan ahead through IMS.com/PlanAhead, an interactive web page that serves as a home base for fans headed to the track this weekend.

The “Plan Ahead” page features detailed information about the entire fan experience at the speedway, including directions, parking, schedule, gate regulations, digital ticket guide, ADA accessibility, etc.

NewsNation affiliate WTTV and Reuters contributed to this report.