PHILADELPHIA -- Left-wing protesters burned American flags, pieces of cloth and – when push came to shove – more plentiful Bernie Sanders signs on Tuesday night outside the Democratic National Convention in Philadelphia.

Unprepared activists quickly ran out of flags and other combustible material and requested donations, in vain. What briefly was an impressive bonfire quickly went out for lack of supplies, as police watched.

In a short period of time, bandana-clad activists on two separate occasions torched flags. First, at around 8 p.m., a large group gathered as the Black DNC Resistance March reached the Democratic convention's main venue after a grueling march of about 8 miles.

"F--k Hillary!" a crowd melodically chanted, swaying back and forth as two full-sized American flags burned on a sidewalk.

The very long protest march of hundreds – or over time, perhaps thousands – featured many chants against the police and against Hillary Clinton on the same evening she received the Democrats' presidential nomination over runner-up Sanders, the socialist Vermont senator who inspired many activists to swarm the convention.

Before long, someone stomped out the flames with the job half-done, as the crowd enthusiastically rushed toward the Wells Fargo Center. A man wearing a yellow bandana dragged the remains along.

Unlike other activists who aggressively chased away reporters, especially those with large cameras, the man amicably described himself as an anarcho-communist and said he was disappointed that whoever brought the flags had purchased nylon banners rather than cotton. He said experienced activists should know better.

The man dragging the remains said two Israeli flags also were burned, though no likeness was visible after the fact.

As he dragged off the mangled mess, an irate passerby warned him, "You're in South Philly," and challenged him to "get smart."

"Soldiers are fighting under that flag for your f--king freedom," the man shouted as a long line of police officers on bicycles rolled by, flanking the protest march.

One activist advised the flag-dragger to leave the charred aftermath. "They'll kill you," he said.

Soon, it was left in the middle of the street. Police officers trailing the march rushed forward to retrieve it.

Melted American flag(s) dumped in street. Cops rush to pick up #demsinphilly pic.twitter.com/UIEbhA3KLw — Steven Nelson (@stevennelson10) July 27, 2016

The second flag-burning was in truth a general-purpose blaze maintained by leftists also wearing bandanas, and took place at around 9 pm. at the gates of the main convention venue. The demonstrators added an Israeli flag and a small U.S. flag to the burn pile.

Then the activists started looking around for another banner. A man nearby had a flag on a piece of bamboo, but they left him alone. Another man milling about wore Old Glory as a cape, but he did not volunteer it to the flames and it was not snatched from his shoulders.

"Who has an American flag they don't want?" someone asked hopefully.

A long line of police watched the bonfire from the other side of a tall, heavy fence placed at the perimeter of the Wells Fargo Center. But they did not act to put out the fire or perform arrests.

A very different situation played out last week in Cleveland, where officers arrested 18 people at or near a flag-burning performed by Gregory "Joey" Johnson and communist demonstrators.

Johnson helped establish the constitutional right to burn U.S. flags when he challenged his arrest outside the 1984 Republican convention in Dallas. But legal scholars say it's still possible to arrest someone for flag-burning if the police action is based on the speech's non-communicative impact, and is not selective prosecution based on the exercise of First Amendment rights.

At the end of the day, Philadelphia police say they made just five activism-related detentions on Tuesday, all after people jumped an outer fence near the convention around 8:30 p.m. Police say four of the five later were arrested by the U.S. Secret Service and charged with a federal crime, 18 U.S. Code 1752, entering a restricted area.

Kris Hermes, a spokesman for the Up Against the Law Legal Collective, says the group was aware of detentions for fence-jumping -- a peaceful act of civil disobedience that resulted in 54 detentions on Monday. Though Philadelphia punishes released fence-jumpers with $50 tickets and no criminal record, the four arrestees from Tuesday theoretically could face prison.

The fire-tending crowd slowly dispersed before midnight. "I could either use a beer or an American flag," a woman said. Her friends encouragingly said "a beer," and the area emptied further.