One Palestinian, caught at the entrance at the Salem checkpoint in the Jenin area, was arrested for carrying an improvised gun, a commando knife and 11 explosive devices, ynetnews.com reported.
The three others were held for questioning by security forces who said they believed all four were intent on carrying out a terror attack.
A Military Police soldier allegedly saw wires sticking out of the clothes of one of the four attempting get past the checkpoint. After the officer ordered the man to undress, he discovered three pipe bombs on his body, ynetnews.com reported.
A search allegedly revealed the remaining weapons. The other three men were not carrying any weapons, police said.
The detainees were locked in a building while police bomb disposal personnel were sent to the area.
An unnamed senior police official said the incident was unusual.
"Eleven devices is an exceptional amount in one time. We've had incidents this year of three or four devices seized at the same time," the official said.