NEW YORK (CBSNewYork) — A New York City doctor has tested positive for the Ebola virus after coming down with symptoms Thursday, officials have announced.

Tests Thursday evening at Bellevue Hospital Center came back positive for Dr. Craig Spencer, Mayor Bill de Blasio said at a news conference.

De Blasio urged New Yorkers not to panic, and reemphasized multiple times along with other officials that Ebola is only transmitted through bodily fluids.

WATCH: City, State Officials Discuss NYC Ebola Patient

“We want to state at the outset – there is no reason for New Yorkers to be alarmed,” de Blasio said.

As CBS 2’s Lou Young reported, EMS crews picked up Spencer just after noon Thursday. He was rushed from a building on West 147th Street in Hamilton Heights where he lives, and taken to Bellevue by a procession of two city ambulances and a police squad car.

Spencer, a 33-year-old physician who works with Doctors Without Borders, came back a week ago from Guinea where he is believed to have been treating Ebola patients.

At the news conference, Gov. Andrew Cuomo said officials believe Spencer came in contact with four people during the time he was infected and symptomatic, and state officials are already talking to those four people.

Those four people include Spencer’s fiancée and two friends – all of whom are healthy, but have still been quarantined, New York City Department of Health and Mental Hygiene Commissioner Dr. Mary Travis Bassett said.

The fourth person who is in contact with the state is the driver of an Uber car, which Spencer took when he went bowling Wednesday night in Williamsburg, Brooklyn, Bassett said. The Uber driver had no direct contact with Spencer, and is not believed to be in any danger, she said.

Uber issued a statement indicating that it also contacted the U.S. Centers for Disease Control and Prevention and the city Health Department, which said the driver and subsequent passengers were not at risk.

Cuomo emphasized that the state of New York has “a full coordinated effort that has been working night and day, coordinating city, state and federal resources.”

“People come through New York, they come through New York’s airports, so we can’t say this is an unexpected circumstance,” Cuomo said.

Cuomo also emphasized that New York state and city are well-prepared for the threat of Ebola, unlike Dallas – where Thomas Eric Duncan became the first person to be diagnosed with the virus in the U.S. and later died.

“We are as ready as one could be for this circumstance. What happened in Dallas was exactly the opposite,” Cuomo said.

“The more facts you know, the less frightening this situation is,” Cuomo added, also stressing the only way to contract the disease is to come into direct contact with infected bodily fluids.

New York State Health Commissioner Dr. Howard Zucker said all processes so far have gone well in treating Spencer, and Spencer can likely make a quick recovery from his illness.

“He was immediately brought to the isolation area that Bellevue Hospital has established for patients that could have Ebola,” Zucker said. “He is being taken care of by an excellent team.”