A stolen beer truck plowed through a crowd of pedestrians in Stockholm Friday — killing four and wounding more than a dozen — in what Swedish officials called a calculated “terrorist attack.”

At least 15 people were hospitalized after the hijacking, with nine in serious condition, according to local authorities.

Two men involved in the attack were later arrested — and at least one admitted to being part of the bloodshed — though neither was believed to be the driver.

Several people were placed under surveillance following the incident as authorities continued to search for the man behind the wheel.

While there was no immediate claim of responsibility, Swedish media on Friday night reported that the first suspect who was caught and confessed is believed to be a 39-year-old Uzbekistan native and ISIS sympathizer, according to the Independent.

The father-of-four reportedly posted jihadist propaganda on his Facebook page and praised the terror group for attacks such as the Boston Marathon bombings.

He was arrested following a police car chase, the Swedish tabloid Aftonbladet reported.

Law-enforcement sources said the second suspect taken into custody is somehow connected to the man, though it’s unclear how.

“Sweden has been attacked,” Prime Minister Stefan Lofven said in a nationally televised statement. “This indicates that it is an act of terror.”

The truck used in the attack had been swiped by a masked man at 2:53 p.m. — as the driver was reportedly dropping off beverages at restaurants and shops.

“We can confirm that the truck was stolen during an unload of products,” Rose-Marie Hertzman, the press officer at Spendstrups, told ABC News. “The driver was just finishing the unload and a man came running up and hijacked the car and drove away.”

The driver attempted to stop the masked hijacker but was unable to and almost got run over in the process, officials said.

The attacker then drove the truck into a street jam-packed with pedestrians, before crashing into a department store.

Photos showed the vehicle jutting out of the upscale Ahlens Mall on Drottninggatan Street after smashing through pedestrians.

A witness said the driver appeared to accelerate as he approached the department store.

“He mowed down eight people there and I saw four bodies a little farther away,” the witness told local news channel SVT.

“A woman with a small child became completely paralyzed and just stood still. I grabbed her and another woman and threw us all into a stairwell.”

Another witness identified only as Nasrin — who immigrated from Syria 10 years ago — cried as she described the carnage.

“I was terrified. I am still shaking. I saw a woman who had lost her legs. It could have been me,” she told SVT. “The truck went at high speed. It crushed everything in its path.

Police reportedly warned people to avoid the area near Sergel’s Square as the drama unfolded. Several people were rushed from the scene by ambulance, according to local reports.

“I went to the main street when a big truck came out of nowhere. I could not see if anyone was driving it but it got out of control. I saw at least two being run over. I ran as fast as I could from there,” a witness told Aftonbladet.

One of the suspects taken into custody late Friday had been seen on grainy surveillance video during the carnage.

“We [still] do not have contact with the driver,” national police chief Dan Eliasson told reporters.

Swedish authorities said they had launched a “preliminary investigation into suspected terrorist crimes.”

“We are determined to never let the values that we treasure — democracy, human rights and freedom — to be undermined,” Lofven said. “Terrorists can never defeat Sweden — never.”

While there was no immediate claim of responsibility, vehicles have been common recent weapons of terror for the Islamic State and other extremists.

In December 2010, Taimour Abdulwahab — a Swedish citizen who had at one point lived in Great Britain — detonated a bomb not far from where Friday’s truck incident took place, killing himself and injuring two passers-by.

In a March 22 attack in London — in which ISIS claimed responsibility after the fact — Khalid Masood drove into a crowd on Westminster Bridge, killing three people and injuring many others, and then fatally stabbing a cop.

With Post Wires