Explosion in New Jersey Along Course of 5K Race Under Investigation An explosive device detonated in New Jersey’s Seaside Park this morning.

 -- An explosive device detonated in the New Jersey beach town of Seaside Park Saturday along the route of a 5K charity race benefiting U.S. Marines and sailors that drew thousands of runners, officials said.

The start of the run was delayed because of the large number of participants, so there were not many people in the area when the explosion occurred. The race was canceled after the blast. No suspects have been arrested in connection with the explosion, according to New Jersey Attorney General Christopher Porrino.

"We are taking every step to ensure the safety of the public and to determine who was responsible for this explosion, which occurred at a time when runners in this charity race could have been in harm's way," Porrino said. "We are grateful that nobody was injured, but this is a serious act of violence against the people of New Jersey. We will not rest until we find the person or persons responsible."

Two officials briefed on the investigation said preliminary results indicate that the devices in the trash can packed enough explosive punch to cause serious injury to people if the race had started on time.

The device was set off with a timer, according to the officials.

One of the officials said the three devices appear to be three components of one device. The main component exploded, but the two secondary components did not.

The FBI has taken the lead on the investigation, a representative for the Ocean County Prosecutor's Office said.

Al Della Fave, a spokesman for the Ocean County Prosecutor's Office, said in an on-camera interview with News 12 New Jersey that the explosion came from multiple pipe-bomb-type devices wired together.

"It's obvious it was meant to affect the run," Della Fave told News 12 New Jersey.

No additional devices have been found in the area, state police said.

The device exploded in a garbage can at approximately 9:35 a.m. Eastern time along the route of a scheduled Semper Five race, the prosecutor's office said.

During a press briefing this afternoon, Della Fave told reporters that aside from the one in garbage pail, no other explosive devices were found in any other areas of Seaside Park.

The race organizers said the run was canceled because an unattended backpack was found in the area.

"Out of extreme precaution, this year's Seaside Semper Five has been canceled due to an unidentified suspicious backpack found at the race site," read a notice on the event's website.

Della Fave told ABC News that the incident was not "a prank" because the device was too sophisticated. Investigators are trying to determine a motive.

"We don't know what this individual's agenda is," Della Fave said.

Officials said runners were scheduled to pass by the area around the time of the blast, according to The Associated Press.

According to the Ocean County Prosecutor's Office, there are no reported injuries or damages to surrounding structures from the blast. The area was evacuated and placed on lockdown as bomb dogs searched for additional devices.

The Semper Five race benefits the MARSOC Foundation, which provides support to active duty and medically retired U.S. Marine Corps Forces, Special Operations Command personnel and their families as well as to the families of marines and sailors who have lost their lives in service, according to its website.

ABC News' Ben Stein contributed to this report. The Associated Press also contributed to this report.