"They have been rescued thanks to the efforts of the police," Kaduna state police spokesman Muktar Aliyu said.
"All of them are a good condition of health," he said, and are now with their embassies.
The four were on private business in Kaduna when they were snatched on the road from the town of Kafanchan to the state capital of Abuja, the latest abduction in Nigeria involving foreigners.
Aliyu said they were rescued at about 05:00 in the same area where they were kidnapped.
"I cannot confirm if there have been negotiations or a ransom paid," Aliyu said, adding that it was "classified information".