Las Vegas shooting: What we know

At least 59 people were killed and more than 500 injured in a mass shooting on the Las Vegas Strip, authorities said Monday. The shooting is the deadliest in modern US history.

The shooter:

• Police served a search warrant on the Mesquite, Nevada, home of Las Vegas shooter, Stephen Paddock, Monday morning. Authorities found weapons and ammunition but could not go into details, according the Mesquite Police Department.

• An additional property in northern Nevada owned by the shooter will be searched soon, Las Vegas Sheriff Joseph Lombardo said in a news conference.

• "We had no knowledge of this individual," Lombardo said of Paddock. "I don't know how it could have been prevented."

• The shooter's brother, Eric Paddock, told CNN: "He was my brother and it's like an asteroid fell out of the sky." He said the last time he spoke to his brother was when Stephen texted asking how their mother was after they lost power for five days in a storm. Eric Paddock said he knew of a couple of handguns and maybe one long rifle but did not know of any automatic weapons owned by Stephen Paddock.

• The shooter had been at the Mandalay Bay hotel since September 28, 2017, authorities said. Hotel employees had been in his room prior to the shooting and did not notice anything amiss, according to Lombardo.

• Police said in a statement that officers "breached the hotel room" where the shooter was located and "found the suspect dead." Authorities believe he killed himself.

• Police do not believe there were any additional shooters.

Casualties:

• At least 59 dead; more than 500 people taken to area hospitals, authorities said.

• Nevada US Rep. Dina Titus said that the biggest need right now is blood.

• This is the deadliest shooting in modern US history. The 2016 Pulse nightclub shooting in Orlando, Florida, previously was the deadliest, with 49 killed.

Investigation:

• The FBI says they have determined no connection with an international terrorist group.

• Authorities say they are not calling this terrorism, at this time. "We have to establish what his motivation was first," said Las Vegas Sheriff Joseph Lombardo, when asked why this event has not been labeled domestic terrorism.

• The shooter had bought multiple firearms in the past, several purchased in California, a law enforcement official told CNN. But those don't appear to be among the 10 or more found in the Mandalay Bay hotel room.

• So far investigators believe the firearms were purchased legally. The suspicion, based on initial reports, is that any of the rifles used were altered in order to function as an automatic weapon, said the official. Among the weapons found so far: a .223 caliber and a .308 caliber.

How the attack unfolded:

• At around 10:08 p.m. local time Sunday (1:08 a.m. ET Monday) the Route 91 Harvest Festival -- a country music concert -- was interrupted by the sound of gunfire, witnesses said.

• Police said the gunman fired on the crowd of about 22,000 people from the 32nd floor of the Mandalay Bay hotel, several hundred feet southwest of the concert grounds.

• Country music singer Jason Aldean was performing when the gunshots began, according to witnesses' cell phone video.

• "The gunshots lasted for 10 to 15 minutes. It didn't stop," said witness Rachel de Kerf.

Reaction:

• DHS says no credible threat involving other public venues, but security could increase.

President Trump tweeted, "My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!"

• The Orlando Police Department, which investigated the 2016 Pulse nightclub shooting, tweeted their condolences to those affected by the Las Vegas shooting.

• From Germany, to the Vatican, to the UK, there has been an outpouring of support from world leaders after the mass shooting.