Islamist militants from the Somalia-based al-Shabab group killed 28 people in an attack on a bus targeting non-Muslims in the same area last week.
The attack on the quarry workers took place early on Tuesday. Witnesses said the victims were caught after
midnight, while sleeping in their tents at the quarry.
A local police chief said the assailants targeted non- Muslim workers at the quarry in Kormey, 15km (nine
miles) from Mandera town.
A man who visited the scene of the attack told the BBC some of the victims appear to have been lined-up, and shot in the head, at close range. Other reports suggested the workers' tents had been sprayed with
Reuters news agency quoted one witness as saying four had been beheaded.
Kenya's Red Cross said on its Twitter feed that security personnel and one of its own teams were on the ground at the site of the attack.
In the attack on a bar in the town of Wajir earlier on Monday night, gunmen reportedly opened fire and hurled grenades, killing one and injuring 12.
No group has so far said it carried out either of the attacks, both of which occurred close to the border with
Mandera County borders both Somalia and Ethiopia, and it is dominated by Somalis, who are largely Muslims.
Many of the quarry workers killed are reported to have come from the south of the country where Christians
Al-Shabab has stepped up its campaign in Kenya since 2011, when Kenya sent troops across the border to help battle the militants.
In one of the worst attacks on Kenyan soil, 67 people were killed last year when four gunmen took over the
Westgate shopping mall in Nairobi.
More recently, dozens of people were killed in a series of shooting attacks in Kenya's coastal districts.
The security situation has led to calls from the opposition and some in the governing party to call for the dismissal of Interior Minister Joseph Ole Lenku and police chief David Kimaiyo.