(CNN) -- President Barack Obama left for Camp David on Marine One Friday but, in a twist that has left some White House reporters scratching their heads, he apparently arrived at the presidential retreat by car.
White House Press Secretary Jay Carney explained the decision not to land at Camp David was made in advance because of the weather. Marine One landed at an alternate site near Frederick, Maryland and the president and his daughter, Sasha, rode in a motorcade the rest of way to the compound.
Because it is customary practice that the traveling press pool is included whenever the president uses a motorcade, reporters naturally wondered why the pool was not part of the trip or even informed that the president would use a motorcade ahead of time.
Meanwhile, CNN's weather team found no signs of stormy weather in the area at the time Marine One departed the White House.
The White House said there were no mechanical issues with the presidential helicopter.
"It was a bit of a surprise because he (Obama) usually does not land here. They usually go all the way to Camp David," said Kristy Rossignuolo, a customer service representative at the Frederick Municipal Airport.
Also Friday, a fighter under the direction of North American Aerospace Defense Command (NORAD) intercepted an aircraft in the vicinity of Camp David. The civilian aircraft left the restricted area and landed at the Martinsburg Airport in West Virginia, NORAD said.
No other details were immediately available on the incident, which was separate from the decision to divert Marine One.
CNN's Jessica Yellin and John Branch contributed to this report