Fiorentina captain and Italy international Davide Astori has died at the age of 31, and all of Sunday's Serie A games have been postponed.

Fiorentina confirmed the news on Sunday morning in a statement posted on the club's official website, with multiple outlets in Italy reporting the defender died of cardiac arrest in his hotel room before the game against Udinese.

"The belief is that the player died of a cardiac arrest by natural causes," Udine prosecutor Antonio De Nicolo said. "It is strange that such a thing should happen to a professional who is so closely monitored without there being any warning signs."

Astori's body was taken to the Santa Maria della Misericordia Hospital for an autopsy.

La Fiorentina profondamente sconvolta si trova costretta a comunicare che e' scomparso il suo capitano Davide Astori, colto da improvviso malore.

Per la terribile e delicata situazione, e soprattutto per rispetto della sua famiglia si fa appello alla sensibilità di tutti. pic.twitter.com/bFGnkReWEC — ACF Fiorentina (@acffiorentina) March 4, 2018

"A profoundly shocked Fiorentina are compelled to announce that their captain Davide Astori, who was struck by an unexpected sudden illness, has passed away," the team said in a statement. "In this terrible and delicate situation, and in particular out of respect for his family, we appeal for everybody to show sensitivity."

Genoa's game with Cagliari, which was due to kick off at 12:30 p.m. local time, was postponed when the players were informed of the news during their warm-up routines. They were visibly shaken as they left the field. After an announcement was made at the Stadio Luigi Ferraris explaining the postponement, fans applauded as a picture of Astori appeared on the big screens inside the stadium.

Torino subsequently announced that their fixture with Crotone would not go ahead before the Lega Serie A confirmed that all of the weekend's remaining fixtures, including the Milan city derby on Sunday evening, had been postponed.

A statement from the league read: "Shocked by this tragic news, all of the family of the Lega Serie A warmly unites around the family of Davide Astori and Fiorentina. All of today's games are postponed due to mourning. Ciao Davide."

Sconvolta dalla tragica notizia, tutta la famiglia della Lega Serie A si stringe attorno alla famiglia di Davide Astori e alla @acffiorentina.



Tutte le gare in programma oggi sono rinviate in segno di lutto.

Ciao Davide. pic.twitter.com/KWa4P0dPHc — Serie A TIM (@SerieA_TIM) March 4, 2018

Fiorentina's league rivals have been sending their condolences.

"AS Roma share the pain the football world is feeling for the loss of Davide Astori. Shocked by this tragic news, the directors, players and all staff of the club affectionately stand by his family through their pain," wrote Roma in a tweet.

L'#ASRoma si unisce al dolore del mondo del calcio per la scomparsa di Davide Astori. Sconvolti dalla tragica notizia, dirigenti, calciatori e tutti i dipendenti della società si stringono attorno al dolore della sua famiglia. pic.twitter.com/62gcg7es3o — AS Roma (@OfficialASRoma) March 4, 2018

"Today there are no colours, but just profound pain. Juventus express their own condolences to the family and to Fiorentina for the loss of Davide Astori," wrote Juventus.

Oggi non esistono colori ma soltanto un profondo dolore. La Juventus esprime le proprie condoglianze alla famiglia ed alla Fiorentina per la scomparsa di Davide Astori. — JuventusFC (@juventusfc) March 4, 2018

Astori began his career at AC Milan but never played a Serie A match before moving to Cagliari. He spent six years in Sardinia and made his national team debut before being sent out on loan to Roma in 2014.

A man who loved football and who grew up as footballer with us. #ACMilan are shocked by the passing of Davide #Astori. It is with great sadness that we offer our deepest condolences to his family and closed ones and to ACF Fiorentina — AC Milan (@acmilan) March 4, 2018

In 2015, he joined Fiorentina on loan, with the club taking up their obligation to buy, and the defender rose to captain the side this season. He played 25 times for his club in 2017-18.

After representing Italy Under-18s, Astori played 14 times at senior level. His debut in March 2011 in a 2-0 victory over Ukraine in Kiev was eventful -- he was introduced as a first-half substitute before being sent off with 15 minutes remaining after receiving two yellow cards.

Astori scored his only international goal in the 2013 FIFA Confederations Cup third-place playoff against Uruguay in Salvador, giving Italy a first-half lead in a match which finished 2-2. The Azzurri won the contest on penalties.

Information from The Associated Press was used in this report.