James Gandolfini's 13-year-old son called for help after his father fell ill and collapsed at a hotel in Rome, Italy following a family day out.

The Sopranos star died on Wednesday (19Jun13) after suffering a heart attack while on vacation with his family ahead of a planned appearance at the Taormina Film Fest this weekend (22-23Jun13).

Details of exactly what happened have now emerged and it has been revealed that Gandolfini's son Michael, from his first marriage to Marcy Wudarski, called for help after his father fell ill in the bathroom of his room at Rome's Boscolo Hotel Exedra.

Hotel spokeswoman Laura Conti tells USA Today, "He (Gandolfini) just felt bad and his son called reception. They (staff) went to the room. And as soon as they saw that something was wrong they immediately called an ambulance that brought him to hospital."

Resuscitation attempts by paramedics failed and Gandolfini was pronounced dead after arriving at the Modini of the Policlinic Umberto I hospital.

Gandolfini was also travelling with his wife Deborah Lin and their baby daughter Liliana, as well as his sister, and the star's assistant Tom Richardson has revealed tragedy struck after the family enjoyed a fun day out sightseeing.

He says, "We all had a marvelous day together, and when he returned to the hotel Jimmy (Gandolfini) went to the bathroom and that is where something happened. His sister said he was still alive when the ambulance took him away."

Hospital bosses have revealed the star died after suffering a cardiac arrest, but his official cause of death will need to be confirmed by an autopsy, which has been scheduled for Friday (21Jun13).

Claudio Modini, director of the emergency room at the hospital, says in a statement, "We were alerted by the director of the Boscolo Hotel Exedra and sent two ambulances. They arrived within eight minutes. They tried to revive Mr. Gandolfini, (who was) in cardiac arrest, (and) was already critical. Efforts to restart his heart at the hospital went on for 40 minutes, with no effect. He was pronounced dead at 10:40 p.m."