Casey Calvert, guitarist of Hawthorne Heights, passed away in his sleep last night. He was 26. Our deepest condolences go out to the family, friends and fans of Casey.

The band posted this statement on their website:

Today is probably the worst day ever. Its with our deepest regrets that we have to write this. Casey Calvert passed away in his sleep last night. We found out this afternoon before sound-check. We've spent the entire day trying to come to grips with this and figure out as much as possible. At this time we're not sure what exactly happened. Just last night he was joking around with everyone before he went to bed. We can say with absolute certainty that he was not doing anything illegal. Please, out of respect to Casey and his family, don't contribute or succumb to any gossip you may hear. We don't want his memory to be tainted in the least. Casey was our best friend. He was quirky and awesome and there will truly be no others like him! His loss is unexplainable. As soon as we know more we will let you know.

Sincerely,

Hawthorne Heights Eron, JT, Micah and Matt

The band's planned winter headlining tour has been canceled. The band have returned home to Dayton, Ohio, to be with Calvert's wife.

UPDATE 1: Billboard is reporting that Calvert may have passed due to an acute asthma attack, although this has not been confirmed by any medical official.

UPDATE 2: Members of Fall Out Boy, Relient K, Plain White T's, the A.K.A.s and Paramore weigh in on Calvert's passing here, and Travis Richter of From First To Last shares his thoughts here.

UPDATE 3: Beverly Fields, a spokeswoman for the Washington, D.C., chief medical examiner's office, told MTV News the results of Calvert's death might not be known for upward of 90 days, pending the results of an autopsy that has already completed. Fields added that the delay is commonplace in cases that are classified as "nonhomicides" (as Calvert's is) and said the cause and manner of his death will not be known until the results of several tests have returned to the examiner's office.

UPDATE 4: The remaining members of Hawthorne Heights as well as Calvert's widow, Ashley, spoke with MTV News regarding his passing. In the interview, the band confirms they will carry on in Calvert's honor, and will not replace him. Read more here.

Below is a video of Hawthorne Heights performing a new song, "Declaratory Judgment," on Nov. 23 in Detroit, hours before Calvert passed away. While the audio quality is poor, you can see Calvert jumping around the stage and smiling at his bandmates, truly loving what he was doing.