The shooting happened on the school's campus and ended outside the school building itself, according to police.
"I was deeply saddened to learn of the horrific shooting at Sparks Middle School this morning," Nevada Gov. Brian Sandoval said in a statement extending his thoughts and prayers to those affected.
About 700 students in 7th and 8th grades are enrolled at the school, located in a working class neighborhood.
"It's not supposed to happen here," Chanda Landsberry said. "We're just Sparks — little Sparks, Nevada. It's unreal."
Senate Majority Leader Harry Reid, D-Nevada, offered his condolences to those who experienced a "traumatic morning."
"No words of condolence could possibly ease the pain, but I hope it is some small comfort that Nevada mourns with them," Reid said in a statement.
The violence erupted nearly a year after a gunman horrified the nation by opening fire in Sandy Hook Elementary School in Newtown, Conn., leaving 26 dead. The Dec. 14 shooting ignited debate over how best to protect the nation's schools and whether armed teachers should be part of that equation.
In a statement on the website of Sandy Hook Promise, a gun control advocacy group, Nicole Hockley, whose son Dylan was killed in the shooting said, "It's moments like this that demand that we unite as parents to find commonsense solutions that keep our children — all children — safe, and prevent these tragedies from happening again and again."
The Washoe County School District held a session in the spring in light of the Connecticut tragedy to educate parents on what safety measures the district takes.
Sparks, a city of roughly 90,000 that sprung out of the railway industry, lies just east of Reno.
Mayor Geno Martini spoke at a morning press conference to assure residents that the community was safe.
"It's a tragic day in the city of Sparks," he said. "This is just an isolated incident."