Gunmen seized a child from a house in Nigeria's southern oil-producing region.
The child was taken from a home in one of the most affluent areas of Port Harcourt, the region's oil hub, Police spokeswoman Irejua Barasua said. She said police were combing the area.
A private security contractor who requested anonymity because he was not cleared to speak to the media, said that a nanny, driver and escort were also taken hostage in the same incident. The child is Nigerian, he said.
Kidnapping has become common in Nigeria's oil-rich but impoverished south, where wealthy oil workers and politicians live next to vast, fetid slums. Around 100 foreigners have been seized since the beginning of the year. Several Nigerians, including the mother of the governor-elect of Rivers State, have also been kidnapped.
Some kidnappers issue political demands, including for the release of leaders imprisoned on corruption and treason charges, and a greater share of oil revenues for their impoverished region. Others merely demand cash.
Most major oil and service companies already required their foreign staff to evacuate their families after a kidnapping incident involving a Filipino woman earlier this year.
Violence has increased since last month's polls, when the ruling party announced a landslide win. The elections were criticized as fraudulent by international and domestic observers.
Although the Delta region produces tens of billions of dollars in oil revenue every year, most of its inhabitants remain mired in poverty with no access to water, electricity or social services.
Nigeria is Africa's largest oil producer, but it is also one of the most corrupt countries in the world.