WATCH: The latest developments in Las Vegas shooting investigation

Latest updates from the 4 p.m. ET police briefing on Tuesday:

  • Authorities have identified all but three victims, Clark County Sheriff Joseph Lombardo told reporters.
  • The total number of people injured has decreased slightly, Lombardo said, due to a "double count issue" at one of the local hospitals.
  • The gunman fired onto the crowd for about nine minutes, Lombardo said, adding that the gunman had also set up cameras outside the hotel room. The sheriff said the shooting was "obviously premeditated."
  • Police reviewing 67 body cameras, as well as other public space cameras.
  • A motive is still not yet known.
  • Crime scene around the Mandalay Bay hotel is still active, the sheriff added.

As investigators work to determine a motive for Sunday's mass shooting in Las Vegas, friends and families have started to identify some of the victims in the attack that left 59 people dead and more than 520 others injured.

Las Vegas officials are scheduled to provide a 4 p.m. ET update on the investigation into Sunday's Las Vegas shooting. Watch their remarks in the player above.

Friends and families of the victims have started to come forward with the names of those who died while attending an outdoor concert on the Las Vegas strip. Sonny Melton, 29, of Jackson, Tennessee. Susan Smith, 53, of Simi Valley, California. Adrian Murfitt, 35, of Alaska. Media outlets will confirm more victims' names in the days to come. Hospital officials told reporters this morning that dozens of victims remained in critical condition.

Authorities identified the suspect as 64-year-old Stephen Paddock of Mesquite, Nevada, who shot from the 32nd floor of the Mandalay Bay hotel at the 22,000 people attending the country music concert below. Las Vegas authorities said Paddock killed himself before officers could gain entry into the hotel room. Investigators have recovered 42 firearms belonging to the suspect, 23 guns in the hotel room and 19 found at his Mesquite home about one hour away.

Paddock has been described as a professional gambler and real estate investor who lived in a retirement community in Mesquite.

President Donald Trump, who spent more than five hours surveying the hurricane damage in Puerto Rico, plans on visiting Las Vegas tomorrow. The president called Sunday's mass shooting an "act of pure evil."

PBS NewsHour will update this story as it develops.

READ MORE: Gunman kills at least 59 people at concert in Las Vegas

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