Cullins, an explosive ordinance disposal officer, had recently recovered from a concussion he suffered in July while dismantling another roadside bomb.
"This is a great loss for the LAPD and for everyone who knew him and witnessed his commitment to upholding his duty and honor as a police officer and a Marine," said Paul Weber, president of the Los Angeles Police Protective League.
Cullins is the second LAPD officer killed this year with the Marines in Afghanistan.
When Marine Staff Sgt. Josh Cullins was firs hurt over the summer, he suffered a concussion while dismantling a bomb.
Shortly after that, dozens of friends and family members put together a video message, more than 10 minutes worth of well-wishes.
The 28-year-old Cullins had been an LAPD officer since July 2008, but was serving with the Marines in Afghanistan as an explosive-ordinance disposal officer.
LAPD officials say Cullins was killed Monday after his unit was called-in to check out a roadside bomb that had detonated.
Just days after the LAPD lost Cullins of, some of Hollywood's top comics got together to throw a fundraiser for wounded soldiers and their families.
The Laugh Factory hosted the fundraiser for the Wounded Warrior Project, an organization that assists wounded members of the military.