A travel writer from Massachusetts is one of the thousands of Americans trapped in the fighting in Sudan as the conflict between two rival generals threatens to explode into all-out civil war.

“There were power cuts, no running water, no access to cash. So I left with only $20,” Lakshmi Parthasarathy, 32, told NBC News on Tuesday after hitchhiking south.

With roughly 16,000 American citizens in the country before the violence broke out almost two weeks ago, the race to evacuate diplomats in recent days has left behind many to fend for themselves in the vast resource-rich African country.

Civilians described frenzied efforts to escape sporadic fighting in the capital, Khartoum, despite a new three-day truce.

“The city was complete mayhem when I left,” Parthasarathy, who is from New Bedford, said via video message from a school that’s been turned into a little refugee camp near Khartoum. Rides to the evacuation ports are going for thousands of dollars, she said.

She described seeing tanks as vehicles carrying civilians, including Sudanese desperately seeking to flee to neighboring countries via land or sea, attempted the dangerous journey out of the capital.

“There were women, children, families who were escaping villages along the way. I thought at the time that only Khartoum had seen the most destruction, but we saw villages that had clearly been devastated by the war,” Parthasarathy said.

As civilians sought ways to escape, fearing that the rival camps will escalate their struggle for power once evacuations are complete, the World Health Organization issued a sobering warning.

There was a “high risk of biological hazard” after one side in the fighting seized a laboratory, the agency’s representative in Sudan said Tuesday, according to Reuters.

The two armed groups have been locked in a battle for control of Sudan, using artillery, airstrikes and bullets in a conflict that has left millions of people caught in the crossfire.

Over 420 people have been killed in the violence, including one American, since the fighting erupted this month, according to the World Health Organization.

“We must all do everything within our power to pull Sudan back from the edge of the abyss,” United Nations Secretary-General Antonio Guterres said Monday.

A stream of foreign powers continued with rescues, often involving military special forces, airlifts and convoys driving past fighters from both sides.

The U.S. military evacuated embassy personnel over the weekend, and Secretary of State Antony Blinken said Monday that the U.S. was considering resuming a diplomatic presence in the country to assist American citizens, many of whom are dual nationals. He said the State Department was in touch with private U.S. citizens to help them find routes to safety.

The U.S. was also assisting its citizens out of Port Sudan, the embassy in Khartoum said Tuesday on Twitter, adding that “border crossings into neighboring countries are possible but routes can be unpredictable or dangerous.”

Blinken said some convoys had been robbed and looted.

The Sudanese military, commanded by Gen. Abdel Fattah Burhan, and the rival Rapid Support Forces, a paramilitary group led by Gen. Mohammed Hamdan Dagalo, said Tuesday they would observe a cease-fire brokered by the U.S. and Saudi Arabia.

But with reports and accusations that the truce was at best being partially observed, those able to flee were scrambling to get to safety.

Thamir Saad Mohamed said he had been sending constant emails to the U.S. Embassy requesting help evacuating his nephews Sajid and Ahmed, aged 2 and 5, who are U.S. citizens.

“I don’t know what will happen in Sudan,” said Mohamed, who’s a Saudi national, adding that he was afraid of losing his family. His sister, Aya Mohamed, a U.S. citizen, had left the two children with her sister the day before the clashes erupted, he said.

So far, the family has received only an automated response, he said.

When approached for comment on their case, the State Department said, “The U.S. Department of State and our embassies and consulates abroad have no higher priority than the safety and security of U.S. citizens abroad,” advising American citizens to provide their contact information in a form on the embassy website.

Denise Bowers, a school teacher and U.S. citizen who lives in Sudan’s capital, said she had been waking up to rattling windows from nearby blasts for days. Faced with shortages of water, food and power, she was now attempting to the cross the border and reach an airport with her husband.

“This has been so surreal. We are out of Khartoum, a 23-hour journey on an overcrowded bus through horrible and some scary situations,” Bowers said in messages sent via spotty internet.

Sudan’s main international airport has been heavily damaged and is closed for commercial operations, forcing many to seek alternative routes out.

While the journey to these airfields and land borders was possible, the roads pass through some of the most hotly contested parts of the country. Khartoum lies about 520 miles from Port Sudan on the Red Sea.

“There is no way to go outside of Khartoum,” said Musa Osman El Sayeed, describing his trepidation about making the perilous journey with his four children and wife. “You can be shot, everything can happen to you in the street,” he said.

“All the streets are captured by the militias,” he said, adding he was happy foreigners could leave Sudan safely to be with their families.

El Sayeed, 55, said neighbors had described seeing bodies lying in the streets for days. An auditor in the capital before the fighting shut down daily life, he said he would try to make it out as soon as he felt it was safe.

“If this war continues for two or three months more, most of the Sudanese people are going to die from poverty because the situation is very, very difficult,” he added.