A woman suicide bomber on Saturday killed two passers-by and her accomplice in an attack in northeast Nigeria, witnesses and security sources told AFP.
Moments before the explosion, the female attacker and her accomplice, had tried to board a bus but were stopped by the driver.
"The suicide mission took place at around 1130 am when two women wearing hijabs tried to board a commercial vehicle but the wary driver resisted," a highly-placed security source said.
"One of the women was wearing the bomb around her waist and it exploded after the bus departed, killing the other woman and two other people," the source added.
According to witnesses, the two women tried to board the bus in the village of Ngamdu, 90 kilometres (55 miles) from Maiduguri, the capital of Borno state, and 40 kilometres from Damaturu, the capital of the neighbouring state of Yobe.
After the explosion, residents of the village shut themselves up in their homes leaving the four dead bodies on the road, witneses said.
Almost 90 people have been killed in explosions blamed on Boko Haram this week alone, all of them at crowded bus stations in northern and central regions of the country.
Nigerian troops, aided by soldiers from Cameroon, Chad and Niger, have bombarded rebel strongholds in northeast Nigeria and claim to have recaptured territory, including Baga last weekend.