(CNN) -- Tributes have been flooding in following the sudden death of Spanish Primera Liga side Espanyol's captain Daniel Jarque at the age of 26 on Saturday night.
Espanyol fans have begun a memorial for captain Daniel Jarque following his sudden death on Saturday.
Jarque passed away around 8pm local time when his heart stopped following a training session in Coverciano, Italy, where the squad are on a pre-season camp.
Reports suggest Jarque was on the phone to his fiancee -- who is eight months pregnant -- at the time and she alerted two of his team-mates, who raced to his hotel room.
Club doctors and Italian paramedics tried to revive Jarque, a product of the Espanyol youth system, but without success.
Most Spanish clubs immediately expressed their condolences and leading footballing personalities have now done the same.
Speaking on the official Real Madrid Web site, club captain Raul said: "As captain, and on behalf of the whole Real Madrid team, I want to express our sincere condolences.
"We will support the player's family and the Espanyol family in any way possible during this very difficult time for everybody.
"He was a great professional and sportsman and this has left us all very hurt. We offer our most sincere sympathies," added Raul.
Jarque's death comes two years after that of Sevilla and Spain defender Antonio Puerta, who suffered multiple organ failure in hospital, three days after a cardiac arrest during a league match against Getafe.
Madrid coach Manuel Pellegrini added: "It is news that you wish wasn't true. It's terrible, it already happened a couple of years ago to Sevilla and the truth is these things have an impact."
Joan Laporta, president of European champions Barcelona -- Espanyol's city rivals -- said on their official Web site: ""We are very shocked by this tragic event.
"We are all in mourning and I wish to express in the name of FC Barcelona our heartfelt condolences to Espanyol on the painful loss of their captain Dani Jarque, and also to his family".
Jarque joined Espanyol at the age of 12, making his debut in 2002, and was handed the captaincy this summer.
Fans have been flocking to Espanyol's stadium since the news broke and have been in mourning outside gate 21 -- Jarque's squad number.
Former Espanyol coach Ramon Moya, who handed Jarque his debut against Rayo Vallecano, was deeply shocked. "I feel like I have lost a son," he told reporters.
"Jarque was a footballer, but he was also my friend. This situation is very difficult for a person. It was as if he was family. I knew him for many years. I gave him his debut and I shared many moments with him. It's very difficult to explain how I feel at the moment."
Another former coach, Ernesto Valverde, insisted Jarque had never had any medical problems previously. "After hearing the news I still haven't taken it in," said the current Villarreal coach.
"He was a player who was super strong, super healthy and very important in the dressing room. We got goosebumps when we heard the news. He was a very strong person but life is like that and it gives you terrible surprises. "
Espanyol, who had been due to play Bologna in a friendly match on Sunday, suspended their pre-season tour of Italy and have flown back to Barcelona.