Four of the injured were people on the ground, including a firefighter. Both crew members ejected from the aircraft before it crashed into the buildings in Virginia Beach. They had minor injuries and were sent to hospital, the Pentagon said.
Thick black clouds of smoke billowed into the air as the apartment complex was reduced to a blackened shell.
Five buildings were heavily damaged by fire, Battalion Chief Tim Riley of the Virginia Beach Fire Department told CNN.
Rescuers were searching the damaged buildings at the Mayfair Mews apartments, less than two miles (3.2 km) from Naval Air Station Oceana, where the F-18D was based.
"We have not had any reported missing people," Riley said.
A volunteer rescuer, Pat Kavanaugh, told CNN he found one of the pilots in the wreckage, still strapped to his ejection seat with a parachute. Kavanaugh and neighbors picked up the seat and carried the pilot away from the flames.
Kavanaugh said the pilot "apologized very much for hitting our complex."
Zack Zapatero, who witnessed the crash, told CNN there were "just large fireballs coming up" into the sky from the crash.
There was no word yet on the cause of the crash.
Amy Miller said she saw "flames underneath the right wing" just before the crash. "I heard the initial impact. Then you heard a boom right after that."
The distinctive, twin-finned tail section of the F-18D landed in the courtyard of the complex of two-story brick buildings.
Dozens of firefighters and emergency workers converged on the scene, smothering the apartment complex with foam.
The plane was part of a training squadron at Oceana, the largest Navy air facility on the East Coast, that prepares replacement Navy and Marine aviators and weapons officers for duty.
Some 250 aircraft are stationed at Oceana with its seven miles (11 km) of runway, 20,000 military and civilian workers and 19 fighter/attack squadrons. The Navy says Oceana is the largest employer in Virginia Beach.
There are 37 tactical squadrons of F-18s operating from air stations worldwide and from 10 aircraft carriers. The Navy's precision air team, the Blue Angels, flies the F-18.
Virginia Beach is on the Atlantic Coast about 200 miles (320 km) south of Washington, DC.