NAIROBI, Kenya (AP): Two bombs killed 10 people and wounded 70 others Friday, tossing bodies into the air at a market in Kenya's capital, while hundreds of British tourists were evacuated from the coastal resort of Mombasa after warnings of an impending attack by Islamic extremists.

The U.S. ambassador has requested additional security and is reducing the number of people stationed at the embassy in Nairobi amid an increase in threats.

No group claimed responsibility for the blasts, which went off minutes apart in the Gikomba market near downtown Nairobi.

President Uhuru Kenyatta, appearing at a previously planned news conference shortly after the bombings, offered his condolences.

But he dismissed the tourism warnings from the U.S. and Britain that led to the evacuations, saying that terrorism is a common problem and not unique to Kenya.

As ambulances and security forces responded to the market bombing, witnesses described a chaotic scene.

"I heard the first blast, then another one," said Gikomba market trader Judy Njeri, who described crouching and crawling on hands and knees after the explosions that wounded some of her colleagues.

"I saw bodies being tossed in the air," she added. "The whole place was thrown into darkness and a lot of dust."

Police Chief Benson Kibue announced the casualty figures.

Security concerns are high in Kenya because of its proximity to Somalia and the al-Qaida-linked group, al-Shabab, which operates there. In September, four al-Shabab gunmen attacked the upscale Westgate Mall in Nairobi, killing at least 67 people.

On Thursday and Friday, TUI Travel, which owns the British tourism companies Thomson and First Choice, evacuated customers and canceled all flights to the coastal city of Mombasa until October. The British government had urged its citizens to leave Mombasa and nearby beach towns.

The U.S. and Britain were among several nations renewing warnings of possible terrorist attacks.

Earlier this week, the U.S. warned for the first time that its embassy itself is taking new steps to increase security "due to recent threat information regarding the international community in Kenya."

On Friday, Ambassador Robert Godec sent a letter to his staff, saying he has requested assistance from the Kenyan police and State Department. Godec said additional police are patrolling the embassy vicinity and that more assets will arrive from Washington next week.

The embassy is also reducing its staffing numbers.

"Unfortunately, the security situation in Kenya, especially in Nairobi and Mombasa, continues to worsen. Since the tragic events of Westgate in September 2013, the number of attacks, threats, and warnings is deeply concerning," Godec said, referring to the assault on the mall.

More than 100 people have been killed in shootings, grenade attacks and small bombings in Kenya in the past 18 months, the U.S. Embassy said. Kenyan authorities, with the help of the FBI, recently discovered a huge car bomb that could have caused a lot of damage.

Al-Qaida detonated a massive bomb by the U.S. Embassy in Nairobi in 1988, killing more than 200 people.

The U.S. Embassy's security posture has increased in recent days. Marines now patrol the embassy grounds in bulletproof vests and helmets. Emergency drills tell embassy staff: "Duck and cover, duck and cover."

"We know from experience whether it's been in Yemen where embassies have been attacked or in Benghazi where our consulate and ambassador was attacked, anything that is a symbol of a foreign country is a potential target," said Scott Gration, a former U.S. ambassador here.

As for the evacuations, many travel companies have insurance policies that don't allow tourists to be in high-risk locations, noted Gration, a retired U.S. Air Force major general who runs a technology and investment consultancy in Nairobi.

Some of the tourists boarding a flight home at Mombasa airport expressed disappointment with the travel company's decision to evacuate them, saying they had felt safe in Mombasa.

"We believe we're safe here where we are in Kenya," said Dave Moor of England. "Everyone has been really friendly, non-threatening. We've had no worries at all, you know, and we're just so upset that you wait all year for your holiday and you've got three days and they send you home without any real reason."

Stefan Arraw of Peterborough, England, called it "a lot of overreaction."

Kenyatta said the warnings strengthen the will of terrorists.

Kenya sees a big drop in tourism activity — a major money-maker — whenever such alerts are issued. Kenyatta said the government would install 2,000 security cameras in Nairobi and Mombasa to help combat terrorism.

Gration said Kenya's coast is a beautiful and mostly safe location.

"My belief is that everywhere there are issues and we all need to be prudent in when we go and where we go," Gration said. "So I don't travel at night, avoid big crowds and lock my doors. Whether you are in Newark, New Jersey, or Nairobi, Kenya, we can all fall victim to crime or terrorism."