Authorities in Madison, Wisconsin said no arrests have been made in the connection with a weekend arson attack at the offices of a prominent anti-abortion group. 

Madison Police Chief Shon Barnes said investigators have collected "multiple" pieces of evidence from the scene of the attack at Wisconsin Family Action and turned the items over to federal authorities. Two Molotov cocktails were also found in connection to the attack, he said.  

"As much as we wish we could be able to solve this case today the forensic process must take time," he said during a Monday update on the investigation. "While we wait, we're combing the area and searching for digital evidence."

WISCONSIN ANTI-ABORTION GROUP TARGETED IN MOLOTOV COCKTAIL ARSON ATTACK 

Authorities said the attack happened around 6 a.m. Sunday. A passerby on their way to the airport noticed flames coming from the office building, Barnes said. The blaze was extinguished within five minutes. 

Wisconsin Family Action President Julaine Appling previously told Fox News that two windows were smashed and Molotov cocktails were tossed inside the group's office, one of which exploded, igniting a fire inside the office that burned furniture and books and sent shards of glass around the room. 

No one was working at the time of the blaze. 

On one outside wall, a message left in spray paint read: "If abortions aren’t safe then you aren’t either." Appling said what was not seen in initial photos and videos from the scene was another wall tagged with the anarchy symbol and the number 1312, which is meant to stand for the phrase, "All Cops are B-------."

Madison police said a Molotov cocktail was thrown into the Wisconsin Family Action office but failed to ignite. A fire was set afterward, they said. 

The attacks came days after a draft U.S. Supreme Court opinion was leaked that suggested the court may soon overturn the landmark Roe v. Wade decision that legalized abortion nationwide.

Wisconsin abortion attack.

Madison Police Chief Shon Barnes gives an update Monday on the arson attack of an anti-abortion group over the weekend. (WITI)

"We're looking at this from the lens, this is a First Amendment protected right," said Robert Payne, Assistant Special Agent in Charge, FBI, Milwaukee. "People have their opinions. And when we violate that, and we use criminal activity or violence in that nature, the FBI and our federal authorities will look at that for all federal statutes in which to investigate."

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Fox News' Danielle Wallace contributed to this report.