US PRESIDENT Donald Trump said yesterday that he was praying for the families of 17 children and teachers shot dead and 14 others injured at a secondary school in Florida.

Police say that 19-year-old Nikolas Cruz, equipped with a gas mask, smoke grenades and multiple magazines of ammunition, opened fire with a military-style rifle on students and staff on Wednesday afternoon.

Mr Cruz, now charged with 17 counts of murder, set off the fire alarm at the beginning of his slaughter so that the corridors were more crowded with kids.