The father of two survivors of a high school massacre in Florida has died after being shot at his convenience store.

The suspected killer was caught on security camera robbing Ayub Ali at his shop in North Lauderdale, before returning a short time later to shoot him.

Two of Mr Ali's four children attended the Marjory Stoneman Douglas High School in Parkland, where 17 people were gunned down in February by a former student.

A manhunt is continuing for the man who killed Mr Ali, 61.

Who is this person? Around 12:40 p.m. July 17, our homicide detectives say he robbed and killed Ayub Ali at Aunt Molly's Food Store in North Lauderdale. pic.twitter.com/2VDoztwWnP — Broward Sheriff (@browardsheriff) July 19, 2018

CCTV footage shows the gunman following the victim behind the shop counter at Aunt Molly's convenience store, before putting a black object to his back.


At one point, Mr Ali is seen putting his hands up, appearing not to put up any resistance.

The man then takes money from the cash register, thought to be about $500, and leaves.

Image: The mass shooting at Marjory Stoneman Douglas high school led to protests over gun laws

However, Broward County Sheriff's Office say the man then came back and shot Mr Ali.

He was taken by paramedics to Broward Health Medical Center, where he was pronounced dead.

Two of Mr Ali's children, a son and a daughter, survived the Valentine's Day attack on their high school.

Nikolas Cruz, 19, is accused of carrying out the mass shooting that led to renewed protests against gun violence in the US and demands for tighter controls on firearms.