Witnesses said gunmen are fighting inside.
The second auto bomb exploded near the former parliament building, and the extent of damage caused by the second explosion is not yet clear.
The reporter said ambulances transported bodies and wounded people from the scene.
According to Somali national news agency (SONNA), former MP Abdinasir Garane and former police commissioner of Daynile district Mohamed Yusuf were among the dead.
Security officials say the bomber who attacked a hotel in Somalia's capital had pretended his truck had broken down outside the gate.
Police Colonel Mohamed Abdullahi says the bomber stopped outside the heavily fortified hotel and pretended to fix the vehicle before finally turning it around and detonating.
The Nasa Hablod 2 is a popular hotel located in the north of the city whose sister hotel, the Nasa Hablod, was hit by Shabaab militants in June 2016, in an attack that killed 11 people. No one has claimed responsibility for that attack.
A huge cloud of smoke rose over the scene and a Reuters witness saw over a dozen wrecked cars and bloodstains in front of the hotel.
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Somali-based insurgent group al-Shabaab claimed responsibility for the attack and said its fighters remain inside the hotel.
Captain Mohamed Hussein said gunfire could still be heard inside the Nasahablod hotel, which is close to the presidential palace and is frequented by politicians and other members of Mogadishu's elite.
Civilians assist a man, injured from a suicide vehicle bomb explosion, at the gate of Nasahablod Two Hotel in Hamarweyne district of Mogadishu, Somalia.
The al-Shabab extremist group has quickly claimed responsibility for a suicide vehicle bomb that detonated outside a popular hotel in Somalia's capital.
A Somali police officer says a suspected suicide auto bomb has detonated near the gate of a hotel close to the presidential palace in Mogadishu.
Its sister hotel, the Nasahablod, was targeted by Al Shabab in a similar attack that killed 11 people in June past year.
A second blast was heard in the area minutes after the first.
Twin auto bombs exploded outside a hotel in Mogadishu, killing at least 10 people in Somalia's capital Saturday, local officials said. The violent group often targets high-profile areas of Mogadishu.