On the day the Nazis ambushed his guerrilla camp in the dark forests outside Vilna, Benjamin Levin could feel the gunshots whizzing past.

One of his comrades fell, and Levin grabbed him by the leg and dragged him from behind, looking for an escape. Blood-splattered, heart pounding, the Jewish resistance fighter ran straight into “a hurricane of bullets” and kept running until he could no longer hear them.

He doesn’t know how he made it out alive, but offers one explanation: At just 14 years old, he was so short, the bullets went right over his head.

For several months before that 1941 attack, Levin and about two dozen others had been hiding in the Lithuanian woods, training and preparing attacks against the Nazis. They slept in makeshift bunkers carved from tangled scrub, drank green pond water that left a sandy film on their throats, and lived on a diet of bitter mushrooms and berries.

“To this day, I don’t know how we survived,” says Levin, who will celebrate his 90th birthday on Passover Monday at a Westchester nursing home.

He is the last survivor of a group of Jewish vigilantes who called themselves the Avengers and vowed to kill as many Nazis as there were Jews who were exterminated. Like his commander, Abba Kovner, who famously exhorted Jews not to go “like sheep to the slaughter,” Levin fought back. His incredible story of heroism and wartime survival was documented by the University of Southern California’s Shoah Foundation and is being told for the first time in The Post.

“This story is important because it breaks the stereotype of Jewish passivity during the Holocaust,” said Mitch Braff, the founding director of the Jewish Partisan Educational Foundation, which chronicles the wartime exploits of some 30,000 Jewish “partisans” who operated throughout the Third Reich. “They were responsible for thousands of acts of sabotage against the Nazis as they headed to the Eastern Front.”

Unlike the larger and more organized group of Jewish partisans founded by the Bielski clan in Poland, whose heroics were chronicled in the 2008 film “Defiance,” Levin’s group never comprised more than two dozen members. But they were a daring fighting force. During the war, Levin and his group destroyed 180 miles of railroad, blew up five bridges and destroyed 40 Nazi train cars. They took no prisoners, preferring to shoot enemies on the spot. They killed 212 enemy soldiers, according to the Jewish Partisan Educational Foundation.

With his diminutive stature, Levin was recruited as a scout and saboteur for the small group, consisting of Jewish intellectuals and revolutionaries who had set up a clandestine base of operations in the Lithuanian forests in anticipation of the Nazi takeover of the country in July 1941. His older brother Shmuel, a fervent Zionist who was 18 when he joined the group, was one of its founders. Eventually, as hostilities escalated, his sister Bluma would also join.

Wiry and street smart, Levin could pass undetected among Lithuanian and Nazi soldiers to courier messages to different factions of the resistance, some of them working out of the Jewish ghetto in Vilna. Desperate Jews entrusted him with their valuables, which he exchanged on the black market for food and medicine. He also helped to blow up bridges, telephone poles and railroad tracks to slow the trains heading to death camps. The youngest member of the group, he learned to use his pistol from a fellow Avenger. Rozka Korczak was one of the few women leaders of the Jewish partisans, and its fiercest warrior.

“At first, I saw this as a game,” said Levin in an interview with Shoah Foundation researchers. “I was reading a lot of books about conspiracy and the Russian underground. For me, it started out as a great adventure.”

And, while he says he can no longer remember how many Nazis he personally wounded or killed, Levin’s acts of sabotage were so numerous that more than 70 years after the end of World War II, Lithuania still has an outstanding warrant for his arrest.

By his own account, Benjamin Levin grew up with “a wild streak.” He was smoking cigarettes by the time he was 8 and hanging out with a gang of young hoodlums on the streets, which caused no end of grief for his mother and father — prosperous Jewish merchants who operated a gourmet food store in the center of Vilna. Before the Nazi occupation, the city was an important hub of Jewish life, and home to more than 100 synagogues.

Levin’s father, Chaim, was an observant Jew but also a Germanophile, fluent in German and schooled in the classic tradition, reading Goethe and Schiller. In the years leading up to the Nazi occupation of the city, he refused to believe the news he heard from his shaken suppliers in other parts of Europe — that Jews had lost all of their rights in Germany, that Jewish businesses were being forcibly taken over by the Nazis. In 1938, the Nazis had gone on a rampage, smashing thousands of businesses, desecrating Jewish cemeteries and synagogues, and rounding up 30,000 Jewish men throughout Germany. Even though he had heard various breathless accounts of the Kristallnacht pogrom, Chaim never imagined Jews in Lithuania were in any real danger.

“My father was a big believer in all things German,” Levin said. “He thought it would all blow over.”

But Shmuel and his comrades saw the writing on the wall. Long before the Nazis seized control of Lithuania in July 1941, Shmuel had already bought himself a pistol and ammunition, which was the price of admission to the group of forest militants who demanded an unshakable sang-froid and ruthlessness from their recruits as well as a weapon and ammunition.

Several weeks into the Nazi occupation, partisan scouts were sending reports about mass arrests and massacres of Jewish men and boys. In Vilna, German soldiers and Lithuanian security forces went door to door, detaining thousands of Jewish men and boys, and sending them on forced marches to the city’s outskirts. During the late summer, more than 21,000 of them were massacred, their bodies dumped into mass graves.

With reports of mass killings in the forest coming from his eldest son, Chaim Levin was shocked into action. He sold the family business so he could buy weapons and ammunition for each member of his family to join the partisans. They followed Shmuel into the forest, but Chaim and his wife found refuge on a farm, where they hid until the end of the war.

By the fall of 1941, all of Vilna’s remaining Jews were scattered. Thousands were forced into two ghettos — a cluster of ancient buildings in the city’s Old Town connected by a bridge. Levin and his brother would continue to operate from their base in the forest, although Levin was able to slip in and out of the ghetto to carry messages to partisan leaders who were trying to organize an uprising.

On one such mission to the ghetto, Levin got caught up in a Nazi “aktion,” or raid, one of the surprise deportations carried out on Jewish holidays to sow panic into the 40,000 surviving ghetto Jews. Levin was forced to hide in an attic. When an infant began to cry incessantly, Levin watched in silent horror as the father took an overcoat and smothered the child with one deft movement.

“I think they killed the baby,” he said. “I saw a lot of things. I saw very noble people become animals. And very plain people become noble. And my mother warned me that there would be worse to come.”

‘I saw a lot of things. I saw very noble people become animals. And very plain people become noble. And my mother warned me that there would be worse to come.’

The worst came after Shmuel went on a raid with a group of his fellow partisans and never returned. His body was never recovered, and Levin doesn’t know how he died.

But Levin barely had time to mourn his brother. By the summer of 1943, SS chief Heinrich Himmler gave the order to liquidate all Jewish ghettos in the Third Reich. Although Kovner had tried to persuade his fellow Jews to resist the Nazis, the planned insurrection failed, and the ghettos were emptied in late September when the Nazis rounded up the remaining Jews and shipped them to death camps. Kovner returned to the forest, and the Avengers helped Russian soldiers who were advancing against the Nazis on Vilna.

Levin and the partisans helped liberate Vilna before the arrival of Soviet forces in the summer of 1944. As they marched through a devastated city, Levin and his comrades rounded up Lithuanians who had collaborated with the Nazis.

“We didn’t keep prisoners,” he said. “There was no discussion. It was a normal thing.” Enemies were shot on the spot.

And so were returning Jews. Although Levin’s parents survived the war in hiding, they were executed by their Lithuanian neighbors when they tried to reclaim the family’s old home in Vilna.

With nothing left for them in Europe, Levin and his sister Bluma, who had survived the war hiding in the forest with her brother, eventually made it to the nascent state of Israel. There, Levin met his future wife, Sara, a Hungarian Jew who had escaped the Holocaust with her family.

“I fought with my parents about him,” said Sara, who spoke to The Post in February, at age 87, from the nursing home where she and Levin spent the last four years of their lives. “First of all, they said he was too short, and I couldn’t wear high heels if I married him.”

They married anyway and moved to Long Island in 1967 with their two young children, a son and a daughter, born in Israel. Levin got a job as a mechanic for the MTA and eventually purchased a gas station and went into business for himself.

The couple had been together for 66 years, and the family — their two children, their spouses and four grandchildren — is looking forward to celebrating Levin’s 90th birthday with a cake on Passover.

Frail and suffering from Alzheimer’s, Levin can no longer recognize photographs of himself, much less remember his birthday. In fact, no one really knows when Levin was born because while he was in the resistance, he had so many false identity documents that by the end of the war he could no longer recall the actual date of his birth. So his family chose the Jewish holiday, which honors the freedom of Jews from Egyptian slavery, as an apt metaphor and a fitting tribute to the birth of a man who had risked everything to fight for the freedom of his people.

“The moment I start to think about this, it comes more and more memories,” Levin told The Post, and immediately broke down in sobs. “We don’t talk about this anymore, but it’s alive inside.”

This year, unfortunately, Levin’s birthday celebration will be bittersweet. Two weeks ago, his beloved Sara died.

At her grave, after he had strained to scatter earth on her casket, Levin addressed his son in Hebrew: “It looks like it’s my time now.”