Not even three minutes had elapsed Sunday night, and D.C. United already was on its heels.

Philadelphia Union forward Andrew Wooten pushed forward, then fed charging midfielder Alejandro Bedoya at the edge of the 18-yard box. He stepped into his shot — squarely with his left foot beside the ball — and delivered a hard attempt on the ground. The ball hit the left goal post and rolled into the back of the net, out of the reach of diving goalkeeper Bill Hamid.

The crowd gasped, but Bedoya wasn’t done: He darted to his right, past the red corner flag, to a TV microphone in the corner of Audi Field. He knelt and grabbed the mic.

“Congress, do something now!” he yelled at the end of a weekend in which two mass shootings left at least 29 people dead. “End gun violence! Let’s go!”

Bedoya’s goal gave his team an early advantage, and D.C. United did not have much of a chance from there as the first-place Union collected three points in a 5-1 road rout.

“It just hit me. . . . I got to say something,” Bedoya said of his comments, which couldn’t be heard by the crowd but were audible on Fox Sports 1’s telecast. “I’m not going to sit idly and wait for things to happen 50 years from now — I want change now.”

“One thing I’ll say is, more guns are not the freaking answer,” he added. “So let’s see. Politicians are politicians, they’re backed by lobbyists and corporations, so things need to change in the way this government is being run.”

Union Coach Jim Curtin supported Bedoya’s stance.

“I’m on his side,” he said. “It’s outrageous. Things need to change in this country, for sure, and I’ll support anyone who speaks their mind and is intelligent and informed on it, every time. That’s what Alejandro is. He’s passionate, he cares, and again, it’s a real issue in our country now that needs change.”

As for the game, it was D.C.’s second four-goal home loss of the season. United entered the night in fourth place but wasted another opportunity to pick up points at home, falling to 9-7-9 (36 points). Philadelphia leads United by six points in the Eastern Conference.

In its past 15 home matches, United has only four wins. It has won only two of its past 13 matches overall. It surrendered more goals Sunday than it had in a regular season game since Oct. 25, 2015.

“They had more guys show up than we did,” United Coach Ben Olsen said. “And that’s a concern.

“We have to learn how to not play ourselves into the game,” Olsen continued. “This has happened a few times: We seem to gain momentum as the game goes on, not able to show up in the right way, with the right quality, on a night the field was poor. A physical game. In some ways it suited them. . . . They took advantage of two mistakes that changed the game.”

A win could have been the jolt United needed after a lousy performance in Chicago last weekend ended in a scoreless tie. Instead, D.C.’s upcoming schedule looks more daunting. As the playoff push begins, D.C.’s final nine-game stretch won’t be easy: United hosts the LA Galaxy next Sunday, then travels to Vancouver the following weekend.

By halftime Sunday, United trailed 2-0, and the crowd was restless: Fans booed the players as they walked to the locker room. The Union had racked up seven shots on target; United had zero. When Philadelphia had the ball, players pounced and found open spaces.

They became more available just before halftime when D.C. midfielder Júnior Moreno was issued a red card. It was the team’s fourth of the season and its first red card in the first half of a game all season. That put United down a man, straining a group that hadn’t been creating quality chances or fending off attacks even at full strength.

Philadelphia’s second goal conjured images of the first, with a player streaking to the left side of the United defense, then dishing to a teammate near the top of the 18-yard box. This time, midfielder Haris Medunjanin found Marco Fabian, whose right-footed chip shot reached the back of the net in first-half stoppage time.

Philadelphia scored again in the 52nd minute, bumping its lead to three with a goal by Kacper Przybylko. Two minutes later, United responded with its only strike of the night, a Frederic Brillant goal that came from a skirmish directly in front of the goal.

The momentum didn’t last. United star Wayne Rooney thundered a long volley ahead of the Union defense, but midfielder Paul Arriola missed his shot attempt from near the goal. The Union tacked on a couple of goals later, and United fans started filing for the exits with more than 10 minutes left on the clock.

“For me, simply this year the ball hasn’t been falling in the back of the net,” Arriola said. “That’s an issue I have with myself. That obviously cost some points tonight. Maybe I put one of the two away when we’re 3-1. . . . It could have made a difference.”