LONDON/WASHINGTON - Seven-year-old Julian Cadman was out in Barcelona with his mother when a terrorists' van struck where they were walking, separating them.

The British-born boy and his mother were reportedly there to attend a wedding, according to The Telegraph.

The family of Julian has gone on Facebook begging for his safe return. His injured mother is in hospital in a serious but stable condition.

An aunt of Julian said the family is desperate for news of their "sweet, bubbly" boy who has been missing since the atrocity struck Barcelona's busy Las Ramblas boulevard on Thursday (Aug 17).

Julian's father Andrew Cadman said he had spoken to his son only hours before he went missing. He was travelling to Barcelona to search for Julian, The Telegraph reported.

Among the 13 victims killed in the terror attack was a 43-year-old American who was on a delayed honeymoon.

Mr Jared Tucker and his wife had gone to the Spanish city to celebrate their first anniversary in the form of a belated honeymoon.

Mr Tucker had gone to look for a restroom and was struck down by the van, his wife Heidi Nunes told KGO television in San Francisco, according to a Reuters report.

Speaking to NBC News about the chaos at the time, Ms Nunes, 40, said: "Next thing I know there's screaming, yelling."

She tried to look for her husband but "got pushed inside the souvenir kiosk" where she stayed "while everybody kept running by, screaming", The Guardian reported.

Mr Tucker's father, Daniel, who worked with his son in the family's pool business, told the New York Daily News: "It's just something we really just don't understand. I don't know what else to say."

Besides Mr Jared Tucker, the other victims included four Spaniards, two Italians, one Portuguese, one Belgian, and one Canadian.

On Friday, the Canadian was identified as Mr Ian Moore Wilson, a grandfather who was on holiday with his wife of 53 years, The Guardian said.

His daughter Fiona, in a statement on Friday, described him as "compassionate, generous, adventurous, and always game for a lively debate, a good book, exploring new places, and a proper-sized pint".

In her statement, the Vancouver police officer also thanked bystanders and emergency workers who cared for her mother and tried to save her father's life, and those who had offered their sympathy and support.

One of the two Italian victims was 25-year-old Luca Russo, who graduated last year in engineering and had just started his first job, The Guardian said.

He was on holiday with his girlfriend, Marta Scomazzon, who suffered fractures in the attack.

Ms Scomazzon, whose parents travelled to Barcelona to be with her, told the Italian news agency Ansa: "We were walking together and then the van hit us. I fell and realised that Luca wasn't there any more. I didn't see him again. His body was swept away."

Mr Russo's sister Chiara posted images on Facebook of her smiling brother, alongside those of his body lying on the ground in Barcelona.

"Help to bring him home, I beg you,'' she wrote.

The other Italian, Mr Bruno Gulotta, 35, was one of the first victims to be identified. He was holding the hand of his five-year-old son but was reportedly died when he tried to shield his family from the car.

His wife, Martina, who was carrying their one-year-old daughter in a sling-style baby-carrier, told friends that she had pulled their son to safety at the last moment, according to Italian media reports.

A manager at Tom's Hardware, where Mr Gulotta was marketing and sales manager, said of his colleague: "Anyone who met him was impressed by his kindness and professionalism."