(Reuters) - Gunmen sprayed bullets at New Year's revelers in two bars in northeastern Kenya Sunday, killing five people, a witness and police said, the latest in a wave of attacks near the border with Somalia.

Kenyan security forces suspect al Shabaab Islamist rebels, who are fighting the Western-backed government in Somalia, are also behind a string of deadly strikes in the border region.

A worker at one of the bars in the town of Garissa said gunmen approached in a vehicle, opened fire and then drove away.

The guys fired from the vehicle. They first shot the guard, (and then) shot more bullets at those who tried to leave and those who were at the entrance, said the witness who declined to be named.

North Eastern provincial police commander Leo Nyongesa said five people had been confirmed dead. A medic, who asked not to be identified, said 28 people had been wounded, including security officers and several women.

I can see ambulances and the military. Local police have taken two bodies and four people who had gunshot wounds to Garissa general hospital, a Reuters photographer said.

Kenyan forces crossed into Somalia in October to attack the al Qaeda-linked al Shabaab militants, whom it blamed for a spate of kidnappings and cross-border attacks on its soil.

Al Shabaab has denied responsibility for the kidnappings and has vowed major retaliation against Kenya.

Kenyan police said on Saturday they were looking for 15 people who they said had information on al Shabaab.

Last week two grenades were hurled at a club in Wajir-district in northeastern Kenya, wounding at least seven people.

Suspected al Shabaab gunmen on Sunday also shot dead a member of a local security committee in the Dadaab refugee camp in northern Kenya, home to more than 400,000 Somalis, Nyongesa said.

The committee, made up of elders and youths in the world's largest refugee camp, helps Kenyan security forces find al Shabaab militants. Another member of the committee was shot dead on Thursday.

Al Shabaab has now resorted to intimidating locals, Kenyans and Somali refugees working with us to restore security at all the camps in Dadaab, said Nyongesa.

Shootings and roadside bombs in the Dadaab camp since Kenya sent troops into Somalia have forced many aid agencies to scale down humanitarian operations. Most foreign aid workers have left the camp.

(Reporting by Noor Ali and Daud Yussuf; Editing by David Clarke and Alessandra Rizzo)