The Ethiopian government blamed the attack on the Ogaden National Liberation Movement (ONLF), a separatist group which have been increasingly active in the remote east and last month attacked a Chinese-run oil exploration field killing 74 people.
"The culprit is none other than a member of the ONLF which is supported by Eritrea," Bereket Simon, senior Ethiopian government official, said.
An spokesman for the ONLF, which demands self-determination for the largely Somali region of Ogaden, denied involvement.
"Our policy is not to attack civilian targets or Jijiga," Adurahmin Mohammed Mahdi, who is based in London, told Reuters news agency. "The ONLF attacks military targets only."