The United Nations Children’s Fund has temporarily suspended humanitarian operations in northern Nigeria, where as many as half a million people need assistance, after gunmen attacked a convoy and wounded two aid workers.

Unicef said in a statement on its website that unknown assailants ambushed the convoy on Thursday as it was traveling from Bama to Maiduguri.

A Unicef employee and an International Organization for Migration contractor were injured and are being treated at a local hospital, in Maiduguri, the statement added.

“The convoy was in a remote area of northeastern Nigeria, where protracted conflict has caused extreme suffering and has triggered a severe malnutrition crisis,” it said.

Two soldiers were also wounded in the attack by suspected Boko Haram members, Nigerian army spokesman Sani Usman said

More than 500,000 people are living in “catastrophic conditions” in Borno state, Medecins Sans Frontieres (Doctors Without Borders) said earlier in the week.

At least 2.7 million people have been forced from their homes by the violent campaign by Boko Haram terrorists since 2009 to impose its version of Islamic law in Nigeria.