An investigation is underway after grenade-like devices exploded at the Mexican Consulate in Murray Hill early Friday morning.

Police Commissioner Ray Kelly says two devices, both packed with explosive powder, were thrown into the rear of the consulate around 3:30 a.m., causing small explosions.

"They are training grenades or dummy-type grenades that were hollowed out and charges were placed in them. One is smooth and the other is pineapple-like, fragmentation-type grenade, but they're not a full-blown grenades. They are training devices,” said Kelly. “You'll see a lot of them as souvenirs, that sort of thing. But both of them were apparently hollowed out and black powder put inside the grenades."

The grenades, similar to the ones pictured above, were thrown separately, and exploded at different times. Three windows were broken in the blast. No one was injured.

Police believe someone on a bicycle was responsible. He is described as a male in his 20s wearing a grey hooded jacket.

Officials at the Mexican Consulate say they have no idea why the building was targeted as they received no previous threats.

“There is no reason to attack any member of the personnel of the consulate,” said consulate official Ramon Xilotl. “Apparently it's only a signal just to create a callous confusion.”

Kelly said the incident is similar to the explosion at the British Consulate on 52nd Street and Third Avenue in May 5, 2005.

"They are remarkably similar," said the police commissioner. "The event that happened [at the Mexican Consulate] happened at 3:50 in the morning. The event that happened at 845 Third Avenue two years ago was about 3:40 in the morning. So you have an individual on a bicycle, you have these two type devices that are used, [and you have that] it happened roughly ten minutes apart from each other."

Anyone with information on the incident is asked to call the Crime Stoppers hotline at 1-800-577-TIPS.