The three, all from Bucks County, each will be charged with two counts of aggravated and simple assault, two counts of recklessly endangering another person, and one count of criminal conspiracy, the District Attorney's Office said in a statement.
The office identified those to be charged as Philip Williams, 24; Kevin Harrigan, 26; and Kathryn Knott, 24. They were expected to turn themselves in with their attorneys Wednesday morning.
The two men were assaulted Sept. 11 near Rittenhouse Square during a confrontation with a group of more than a dozen people, most of them from the suburbs, who were in Center City to celebrate a birthday, police said.
The encounter became heated and violent, and some in the group hurled antigay slurs, authorities said. By the time it was over, both men had been seriously injured. They had facial fractures and had to be briefly hospitalized. One had to have his jaw wired shut.
The case cannot be prosecuted as a hate crime because no such protection exists in Pennsylvania. It has spurred a widespread outcry for changes to the state's hate-crimes statute to include crimes motivated by sexual orientation, including calls to do so by legislators and local leaders including Police Commissioner Charles H. Ramsey.
On Tuesday, District Attorney Seth Williams, in announcing the charges, called the incident "a vicious attack" and thanked the public for sending in tips.
"An assault on people because of their sexual orientation has no place in Philadelphia," he said.
The couple, whom friends have described as very private, thanked law enforcement and the community for their support in a short statement released after the charges were announced.
"We are thankful the D.A. is working so hard to make sure this doesn't happen again in Philadelphia," they said. "Finally, we ask you to keep your comments regarding the suspects respectful and non-hateful."
Caryn Kunkle, a friend of the couple, said they were relieved by the news of charges but "sad that we're having this conversation - that something like this is what it takes to trigger hate-crime change."
They asked for people to attend a rally at LOVE Park at 2 p.m. Thursday to call for changes in the state hate-crimes law.
On social media Tuesday night, some expressed disappointment that more members of the group were not being charged.
Law enforcement sources said that some members of the group were not involved in the physical encounter. "We're locking up the ones that evidence showed punched the participants," one source said.
None of the three to be charged has given a statement to police.
Many of those in the group were Archbishop Wood High School alumni, including an assistant basketball coach who resigned after the incident. Last week, an archdiocesan spokesman said the coach would have been terminated if he had not resigned. The coach is not one of the three people who will be charged, and a law enforcement source with knowledge of the investigation said the man had tried to break up the fight. He was not involved in the assault, the source said.
A spokesman for the archdiocese declined to comment Tuesday night, saying it was a personnel matter.
Under the glare of national attention, the case proved time-consuming for detectives tasked with locating, identifying, and attempting to interview 15 people captured on a bank surveillance video in the moments before the attack - then parsing through their various accounts.
Capt. Frank Banford of Central Detectives credited "an extremely thorough investigation" by detectives and thanked the public for calling in tips about the assault.
After police posted the video online, Twitter users also called in tips, stemming from a crowd-sourced sleuthing effort.
"Tip lines brought in a lot of info," he said. "We got a lot of names, a lot of calls from people who knew these people."
Some in the group began contacting investigators through their attorneys to come in for an interview.
By last Tuesday, Banford said, investigators had identified all 15 people seen in the footage and then went about scheduling interviews, staggering the interviews so they could review each before the next and build an understanding of the assault.
"We wanted to make sure we had the best picture of what happened here," Banford said. "Any job like this, where you rely on people cooperating with you, it takes time."
And there were other aspects of the investigation that needed to be sorted out, a law enforcement source said.
Police initially reported that one of the men had been robbed of his bag with his wallet and credit cards inside. Investigators found that a witness who was not with the group had picked up the bag after the assault, mistakenly assuming it was a member of the group's, and then left it at a bus stop, where someone else rifled through the bag and used one of the victim's credit cards.
The couple have said that the incident began after one of them bumped into a member of the group, and another member of the group asked whether the two were dating, using profane language. Then, they said, they were attacked.
Eventually, police would interview seven members of the group and four other witnesses. Slowly a portrait of the encounter emerged.
Law enforcement sources said they believe the incident began when one of the members of the group bumped into one of the victims. Words were exchanged, then pushing, shoving, and punches.
"There was definitely antigay language used," a source said.
Another law enforcement source said that after some in the group became convinced that one of the women had been struck, one of the men facing charges, Williams, stepped forward and punched both victims, knocking one unconscious.
Kunkle, the couple's friend, has said the victims deny hitting any of the women.
The sources said some members of the group cast the altercation as a mutual fight.
Banford dismissed that suggestion. "There is no good explanation for the damage that was done to these guys," he said.
On Tuesday night, a man who answered the door at Williams' address in Warminster declined to comment or provide the name of Williams' attorney.
A person who answered the door at Harrigan's Warrington house also declined to comment.
Louis Busico, a lawyer for Knott - daughter of Chalfont Police Chief Karl Knott - said his client "completely denies being involved in criminal conduct that evening."
He said she was present while the incident took place but never hit anyone.
"She was out with a friend for a good time, celebrating a birthday, and the last thing on her mind was to get involved in an altercation with anybody," Busico said.
Inquirer staff writers Allison Steele and Michaelle Bond contributed to this article.