Philadelphia's mayor has apologized after he was photographed dining indoors at an out-of-state restaurant, even though restaurant dining rooms in his remain closed due to the pandemic.

In a series of tweets Monday, Philadelphia Mayor Jim Kenney (D) said he understands the frustration some felt when photos surfaced that showed him eating indoors at a friend's restaurant in Maryland.

"Restaurant owners are among the hardest hit by the pandemic. I'm sorry if my decision hurt those who've worked to keep their businesses going under difficult circumstances. Looking forward to reopening indoor dining soon and visiting my favorite spots."

Philadelphia will allow restaurants to allow diners to eat indoors beginning Sept. 8, as long as seating is restricted to 25% capacity, with a limit at four people per table.

Some restaurant owners in the city slammed Kenney for his decision to travel out-of-state to eat inside a restaurant. In an Instagram post, Marc Verti decried Kenney's trip to Maryland "while restaurants here in Philly close, suffer and fight for every nickel just to survive."

"I guess all your press briefings and your narrative of unsafe indoor dining don't apply to you," he wrote.

Prior to Kenney's apology, the mayor's office pointed out that the county he visited had less than 800 COVID-19 cases, while Philadelphia had more than 33,000, calling them "drastically different circumstances."