Twelve people were killed and dozens more injured in this morning’s shooting at the Aurora, Colorado, movie theater, but at least one person is still unaccounted for.

No one has heard from Alex Sullivan since late last night, when he checked into the theater on Twitter.

Well-wishers tweeted their support for Alex and his family:

Apparently, Sullivan’s Twitter handle was @sully_2003:

And his avatar:

His last tweets expressed his excitement about seeing “The Dark Knight Rises.”

Today was also his 27th birthday.

Our thoughts and prayers are with Sullivan’s family. May they find peace.

Update: Alex Sullivan is confirmed dead, according to the latest news reports.