Hundreds of people have fled to a military airstrip in Kenya’s Mandera region amid fears that militants could launch a new assault.
Many of them are non-Muslim civil servants who are demanding that the government evacuate them from the region, a BBC reporter says.
Al-Qaeda-linked al-Shabab gunmen killed 28 people in a bus attack on Saturday.
Kenya’s President Uhuru Kenyatta is under growing pressure to end attacks by the group.
Al-Shabab is based in neighbouring Somalia, but has stepped up attacks in Kenya since 2011, when Kenya sent troops across the border to help battle the militants.
The BBC’s Wanyama Chebusiri, in Nairobi, says the opposition and some ruling party MPs are calling for an overhaul of Kenya’s security agencies, including the dismissal of Interior Minister Joseph Ole Lenku and police chief David Kimaiyo.
Mr Ole Lenku has flown to the restive Mandera region in an attempt to allay the concerns of people, our reporter says.
There are no reports of a specific threat, but many people in Mandera are worried that al-Shabab could strike again, especially as the festive season approaches, he adds.
Six unions – including those representing doctors, teachers and civil servants – have advised members to leave until security forces can ensure their safety.
The call could affect more than 10,000 teachers and 16,500 civil servants in major towns such as Mandera, Wajir and Garissa