Robert Hawkins, 19, opened fire on Christmas shoppers in a local shopping mall on Wednesday at around 2:00 p.m. local time (8: 00 p.m. GMT). He then turned his weapon on himself. A suicide note was later found.
"Now I will be famous," the suicide note read, his landlady told CNN.
Hawkins had suffered from depression and had recently been fired from a McDonald's fast-food restaurant, KETV reported. The suicide note was also reported to include a remark by Hawkin's that he wished "to go out in style".
Bush had been in Omaha earlier in the day for a fund raising event, and a White House statement said that, "The president is deeply saddened by the shootings in Omaha, Neb., earlier today. His thoughts and prayers are with the victims and their families this evening."
The U.S. has a long history of gun rampages. The Omaha massacre comes some seven months after a high-profile shooting at Virginia Tech, when Seung-Hui Cho, a Korean-American, killed 32 people before killing himself.
In April 1999, two students at a Columbine high school opened fire on classmates, killing 12 teenagers and a teacher. The boys also then killed themselves.
Gun control is a controversial issue in the U.S., where the "right to bear arms" is enshrined in the Constitution.
However, next spring, the country's Supreme Court is set to consider the law for the first time in nearly 70 years. Handguns are currently banned in Washington, DC, and the court is to rule on whether or not the ban complies with the Second Amendment. The final ruling is due in the summer of 2008, and could lead to the issue becoming a factor in the November presidential election.
Despite the ban on handguns, the U.S. capital remains one of the country's worst for murder rates, with 169 cases in 2006.
An estimated 60 million people own a combined arsenal of over 200 million firearms in the U.S.
