Cairo's Museum of Islamic Art—home to almost 100,000 priceless artifacts that comprise one of the world's most important collections of its kind—was extensively damaged when a car bomb exploded early Friday morning outside police headquarters across the street.

The blast was the first of four that rocked the Egyptian capital today, reportedly killing at least six people and injuring more than 90.

As the first bomb blew a crater into Port Said Street, it ripped into the facade of the two-story museum, which is more than 100 years old. Intricate designs in the Islamic style were pulverized.

Immediately after the blast, messages on social media indicated that the damage to the collection was likely to be devastating.

But in a phone interview Friday afternoon, cultural heritage expert Yasmine Dorghamy said, "It isn't as bad as we feared."

Dorghamy, editor of Al Rawi magazine, arrived early to help rescue artifacts and was able to speak with museum staff who were allowed into the building.

"They're estimating that 20 to 30 percent of the artifacts will need restoration," she said. "The Fatimid ceramics right near the entrance are happily intact, but at least three of the glass mosque lamps were destroyed." (The Fatimid Caliphate ruled much of northern Africa from 909 to 1171.)

Inside the museum, ceilings collapsed. Half-fallen building material now poses a safety hazard to anyone entering the building.

Although the ceiling debris smashed the glass in display cases, the framework of the cases was able to protect many artifacts, Dorghamy says.

The museum staff has now moved most of the collection to labs and storage facilities in the basement of the building, where a full assessment of damage will take place as soon as possible.

View Images The force of the blast blew out the Museum of Islamic Art’s windows, shattering display cases and fragile artifacts. PHOTOGRAPH BY AHMED GAMEL, AFP/GETTY

During his inspection tour of the site with a reporter from Egypt's Al-Ahram news organization, Minister of State for Antiquities Mohamed Ibrahim described the galleries as "topsy turvy," and said the destruction was a "great loss" for Egypt and the world.

"It's a crime scene," said University of Alabama Egyptologist Sarah Parcak in a phone interview. "The bomb went off, and there's now major investigations going on by the police and the security forces."

The museum curators and staff have been allowed to go inside and begin an initial assessment. They may find water damage as well as blast debris, since hoses were deployed to douse fires after the explosion.

"All the museum's windows exploded," says Parcak, a National Geographic Society research fellow. "So the survival of artifacts depends on where they were in relation to the windows, and how sturdy their material is. The beautiful glass vases are probably gone."

The museum building dates back to 1903. It reopened in 2010 after a multiyear renovation that cost $10 million.

Twenty-five galleries on the main floor housed one of the world's most important collections of Islamic art—some 2,500 works in wood, plaster, metal, stone, ceramics, calligraphy, and textiles from Egypt and other countries, representing the entire sweep of Islamic history.

"This museum displayed the foundations of a great religion," says Parcak. "It celebrated the artistic beauty and poetry and elegant objects that were used in daily life and in mosques from the earliest years of Islam."

Almost 100,000 additional artifacts were in storage in the basement.

The collection included one of the rarest copies of the Koran, a gold-inlaid key to the sacred Kaaba (the building that houses the black stone kissed by Mohammed) in Mecca, Ottoman-era ceramics, Persian carpets, ancient scientific instruments, a dozen glass mosque lamps from the 14th and 15th centuries, and a restored Mamluk-era (1250-1517) water fountain inlaid with semiprecious stones, green onyx, and colored mosaic tiles.

The Egyptian National Library and Archives, in the second floor of the same building, was also affected. One Facebook report said that more than half a dozen manuscripts were destroyed, and others were damaged.

Four historic mosques in the area were also damaged, along with other buildings in an estimated 160-foot (50-meter) radius of the blast.