Investigators are still trying to establish a motive behind the massacre of 19 children and two teachers at a Texas primary school this week.
Salvador Ramos, 18, carried out the mass shooting at Robb Elementary School, Uvalde, on Tuesday local time.
Ramos was killed by responding law enforcement, leaving a community reeling and renewed calls for gun control ringing out through the US.
Here's what we know about how the latest US mass shooting played out.
May 17: Ramos buys an assault rifle shortly after his 18th birthday.
May 18: Ramos buys a quantity of ammunition.
May 20: Ramos buys a second assault rifle. The bullets and the guns were all purchased legally.
May 24, 11am: Ramos messaged a 15-year-old girl in Frankfurt, Germany, with whom he'd been speaking online since May 9.
READ MORE: What we know about the victims of the Uvalde school massacre
He was upset because his grandmother was talking to AT&T about his phone.
Minutes later, he messaged the girl to say, "I just shot my grandmother in her head."
"Ima go shoot up a elementary school right now."
His grandmother fled the house and remains in hospital.
Ramos got into the car and drove away.
11.30am: Ramos' car crashes near Robb Elementary School. He gets out, wearing a bulletproof vest and carrying a rifle.
A school resources officer approaches him, but is unable to halt the 18-year-old.
11.32am: Ramos exchanges gunfire with police and enters Robb Elementary School, where hundreds of primary-aged students are enrolled.
He moves through the school until he finds a class full of students, and opens fire on them.
11.43am: A lockdown for the school is announced. Law enforcement officers corner Ramos in the classroom and kill him.
12.17pm: The shooting is announced by the school district on social media.
12.23pm: Parents are asked to come and pick up their children.
1.06pm: Police report the shooter was killed by responding officers.
