As Israel and Iran continued trading missile strikes Wednesday, some U.S. citizens have begun making plans to evacuate Israel — and for many young people on tours or studying, it has been bittersweet. 

Some, like University of Michigan junior Julia Cohen, had arrived in May with hundreds of other college students to participate in the Birthright Onward program, which provides internships and fellowships in Israel to people of Jewish descent. She had been dreaming of studying in Israel for years and, after much consideration, her parents decided to support their daughter's decision in April.

Cohen recently found herself staying at a hotel in Southern Israel after nights of Iran and Israel exchanging missiles, her mother told CBS News from New York. 

"They were running back and forth to bomb shelters in Tel Aviv," said Marnie Cohen, who had booked return flights for her daughter to Barcelona, then onward to the United States.   

As of Wednesday, at least 24 people have been killed by Iranian missiles that slipped through Israel's robust air defenses, according to Israeli officials. The U.S.-based Human Rights Activists in Iran organization, which relies on a network of contacts in the country, said Tuesday that it had documented at least 452 deaths in Iran since Israel launched its attacks.

President Trump said Wednesday he had not yet decided whether the U.S. military would join Israel's ongoing attacks on Iran. Sources told CBS News Mr. Trump has approved attack plans on the country, but a final decision to strike had yet to be made.

The U.S. Embassy in Jerusalem told U.S. citizens in Israel Thursday morning that the State Department was "planning for contingencies to assist with private U.S. citizens' departure from Israel."

"We will alert the U.S. citizen community if there is additional information to share regarding departure options," the embassy said in an email message to Americans who had enrolled in the State Department's Smart Traveler Enrollment Program (STEP).

"If the U.S. government provides departure assistance from Israel, options would most likely include travel to a nearby, safe country," and not travel all the way back to the U.S., the embassy said. It asked Americans in Israel interested in leaving the country to fill out an online form.

After Israel's airspace closed, Birthright Onward moved around 300-400 students out of Tel Aviv, and parents started to explore alternatives to get their children out of the country, Marnie Cohen said. It is not clear how many students are currently in Israel. 

Birthright aims to bring 50,000 Jewish young adults, a portion of whom attend the Onward program, to Israel every year. CBS News reached out to Birthright for comment on how they are assisting U.S. citizens on their tours currently stranded in Israel, but did not receive responses before publication. 

Cohen said her daughter's roommate exited through Jordan, taking a car to the capital of Amman and flying from there to the United States. Other students took a boat to nearby Cyprus and are waiting for flights there. Still, Marnie Cohen said, even though her daughter knew of the danger, she didn't want to leave. 

Lauren Field arrived in Israel from Connecticut the day before the conflict started — and a few days before the U.S. raised its travel advisory for Israel to Level 4, the highest level — to visit her 20-year-old son studying in Tel Aviv. She, her husband, son and teen daughter have been waiting in southern Israel for evacuation. 

Her family enrolled in the Smart Traveler Enrollment Program (STEP) and was waiting to hear the next steps on evacuation plans from the U.S. government. She said she hadn't heard yet from the federal government but had been in touch with local legislators and nonprofits. 

She said her son had mixed feelings about leaving Israel. 

Field, who visited Israel once before in 1990, said even with the uncertainty everyone is facing, she and her family felt fairly safe. 

"We've met the most amazing, wonderful people and feel more connected than we ever have," Field said.