An Army psychiatrist suspected of opening fire on fellow soldiers at Fort Hood cleaned out his apartment and left a phone message saying goodbye to a friend in the days before the rampage that left 13 people dead, neighbors said Friday.

Authorities said the 39-year-old Maj. Nidal Malik Hasan went on a shooting rampage Thursday at thesprawling Texas base. He was among 30 people wounded and remained hospitalized Friday in a coma, attached to a ventilator. Hospital officials said some of the wounded had extremely serious injuries and might not survive.

Investigators were trying to piece together the details of the worst mass shootings ever on an American military base. Some who knew Hasan said he may have been struggling ...