Police investigating reports of marijuana plants say they found what appeared to be explosive devices at a Long Island house and evacuated 20 nearby homes as a precaution.     

Police officers went to the home on Narrow Lane in Woodmere after an alarm went off Tuesday afternoon and found a 53-year-old man without identification, according to authorities.

"As soon as he opens the door, the officers are struck by a very pungent smell of marijuana," said Deputy Inspector Kenneth Lack, of Nassau County Police. "They also see what appears to be a black semi-automatic handgun right inside the door, as well as what appears to be two military-style hand grenades."

Police took the man into custody and evacuated about 20 homes on the block. They brought in the bomb squad and began to search the home for whatever else might be inside.

Police are trying to determine if the apparent grenades are real and how to dispose of them.

Meanwhile, neighbors looked on in confusion. One man who only gave his name as Stu said the an elderly couple lives in the home and is out of town.

"I don't know what this is all about. There's gotta be another reason for this," said Stu. "I think there's an overreaction going on. There's no way those kind of people are going to ignite something, blow anything up."

Police said that the man in custody is not the homeowner. Unspecified charges are pending.