The coffee was flowing at Philadelphia restaurants as they opened their doors with coronavirus-related safety measures in place Tuesday morning.

Philadelphia officials announced last month that indoor dining would return to city restaurants on Sept. 8. Only four diners are allowed at a time at one table -- and the number of total diners is limited to 25% of each restaurant's capacity.

The rule requiring no more than four seats at a table is to discourage mixing people from different households, City Health Commissioner Dr. Thomas Farley said.

Philadelphia's popular restaurant scene was shuttered in mid-March as COVID-19 spread; limited outdoor dining was allowed starting in June.

Also among the restrictions on restaurants: Servers must wear face masks as well as face shields. Diners at separate tables must be at least 6 feet apart or have an impermeable barrier between them. Diners must wear masks unless they are eating.

There will be no seating at bars, and alcohol can't be served without food. Last call for all indoor dining orders will be at 11 p.m. and restaurants must close by midnight.

Eateries can also opt to keep outdoor seating areas open.

Restaurants must install physical barriers where maintaining 6 feet of distance is difficult, including in kitchens and at cash registers, host stands and food pick up areas. And, restaurant workers must be screened for symptoms before every shift.

The restaurants also are being urged to increase ventilation and promote the state's contact tracing app.

In some cases -- including the use of face shields -- those rules are more restrictive than in suburban counties.

The city plans to send inspectors in to restaurants to ensure that restaurants comply with the new rules, Farley said. "We will be quick to close restaurants" that don't comply.

And, on Tuesday, Gov. Tom Wolf announced that dining throughout the state can expand to 50% capacity later this month, but it's unclear if Philly will follow suit as they operate on their own timetable.

Last month, the city also announced it would allow theaters, including movie theaters and live performance venues, to reopen as well on Tuesday. The total attendance of those venues is limited to 50% capacity and a maximum of 25 people, meaning even large venues can seat only 25. All attendees must wear masks. No food or drink can be sold.