ORLANDO, Fla. - Federal investigators released information as to what was happening inside the Pulse nightclub after a gunman started a deadly assault that was the worst mass shooting in modern U.S. history.
A printed, partial transcript of the conversations between the gunman Omar Mateen within the Pulse gay nightclub and Orlando police negotiators were released Monday morning.
The audio of the 911 calls will not be released, according to the FBI. Five hundred interviews, 117 vehicles released and 600 pieces of evidence have been analyzed since the shooting, according to the FBI. Thousands of tips have been called in, officials said.
[READ: Transcript of conversations between gunman, police | VIDEO: Final moments in club ]
"This investigation is one week and one day old, and it may last months, it may last years," said Ron Hopper with the FBI.
The timeline, which was crafted with radio transmissions and 911 calls, shows officers were in the club within minutes and that they engaged the gunman with gunfire, police said.
Orlando police said the department transmitted a shots-fired call at Pulse at 2:02 a.m. June 12 and at 2:04 a.m., additional OPD units arrived. At 2:08 a.m. officers engaged the shooter and at 2:18 a.m., an OPD SWAT call out was initiated.
At 2:35 a.m., the shooter contacted 911 and had a 50-second call in which the FBI described him as "chilling and calm" and speaking in a deliberate manner.
The gunman engaged in three additional conversations with OPD negotiators at 2:48 a.m., 3:03 a.m. and 3:24 a.m.
"No stone is being left unturned," the FBI said, adding that they will not answer any questions at the Monday news conference.
"The brave men and women of law enforcement should not be second-guessed," said US Attorney Lee Bentley. "They saved lives."
Orlando Police Chief John Mina said that he was extremely proud of the heroic actions of the officers and said that they saved many lives the night of the shooting.
Mina said he is confident in his choice of waiting three hours before confronting Mateen saying during those hours, the shooter was contained in a hostage situation and on the phone with negotiators while officers were inside of the club rescuing people from dressing rooms.
"It was the right decision at the right time and I stand by that," Mina said. "I would make the same decisions standing here today."
Hostages like Miguel Leiva took cellphone video while he and others stayed as silent as possible and said that whenever Mateen heard a cellphone ring he would check the area and start shooting.
Mina repeated more than three times at the news conference that there were no gunshots until SWAT blew up the wall to get the hostages out.
"There was no other gunfire until the hostage rescue operation took place," Mina said.
When Mina was asked if gunfire hit or killed any of the hostages, he said, "those killings are on the suspect and the suspect alone."
Orange County Sheriff Jerry Demings said that they had been preparing and training for events such as the Pulse shooting.
"Our community remains a safe community," Demings said. "It is a vibrant, resilient community."
The release is coming a day after tens of thousands of people held a candlelight vigil in the heart of downtown Orlando for the 49 victims who died in the massacre. The victims also were remembered at church services and at makeshift memorials throughout Orlando.
"As a community, it's important that we gather together to show our support because only together can we move forward," said Gabrielle Claire, a musician and Universal Orlando worker who says she knew three Pulse victims who died. She was holding a "Hugs for Healing" sign at the vigil and numerous strangers came up to hug her.
Armed with a semi-automatic weapon, Mateen went on a bloody rampage at the club June 12 that left 49 people dead and 53 others seriously hurt. Mateen died in a hail of gunfire after police stormed the venue.
"We are hurting. We are exhausted, confused, and there is so much grief," said Larry Watchorn, a ministerial intern, during a sermon Sunday at Joy Metropolitan Community Church in Orlando, whose congregants are predominantly gay.
Florida Gov. Rick Scott described the attack as "devastating" while praying at the First Baptist Church of Orlando on Sunday. He said the gunman targeted "two very vulnerable populations."
"But here is the positive out of it ... people have come together," Scott said. "There are so many people who have done so many wonderful acts."
Around Orlando, people left balloons, flowers, pictures and posters at a makeshift memorial in front of the city's new performing arts center and at Orlando Regional Medical Center where 49 white crosses were emblazoned with red hearts and the names of the victims.
The crosses were built by a Chicago carpenter with a history of constructing crosses for victims of mass shootings. Greg Zanis drove from Illinois to Orlando last week and installed the crosses at the medical center, where many of the 53 shooting victims who survived were taken for treatment.
He said Sunday that the crosses are a message for people of all faiths: "Quit judging and start loving."
A rainbow appeared over Lake Eola Park Sunday evening as tens of thousands of people turned out for an evening vigil to honor the victims of the shooting. The park was filled with people holding white flowers, American flags and candles.
One of those people attending, Traci Hines-McKenzie, said the timing of the rainbow was perfect.
"You know that's a sign," she said.
Dr. Khurshid Ahmed was part of a group of Muslim-Americans at the vigil who held signs reading, "Muslims Condemn Extremism." Investigators have said Mateen reportedly pledged allegiance to the Islamic State group, and a letter from the chairman of the Senate Homeland Security Committee, Republican Ron Johnson of Wisconsin, said Mateen wrote on Facebook that "real Muslims will never accept the filthy ways of the West."
At the end of the vigil, people held up their candles as the names of each victim were read, creating a ring of fire around Lake Eola. They chanted "One Orlando," ''Orlando United" and "Somos Orlando," Spanish for "We are Orlando."
"That event has gotten the attention of the world," said Evania Nichols, an Orlando resident. "And, for Orlando — a city that's always been incredibly inclusive no matter your skin color, no matter your background — it's brought about a movement that I think is starting here and I really hope continues."
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