Pixar/Disney's animated film Onward retained the top spot for the second week, but saw estimated ticket sales for the Friday-to-Sunday period plummet from last week's $39 million to just $10.5 million, Exhibitor Relations reported Sunday.

Overall, the box office appeared to be at a 20-year low of around $55 million, a figure even lower than the first two weekends after the 9/11 attacks in 2001, according to the Hollywood Reporter website.

It quoted one executive as estimating that 100 of North America's 5,000 theaters had closed completely, with others likely to follow.

In second spot for the weekend was new Lionsgate film I Still Believe, at $9.5 million. The cast of the Christian romantic drama includes country singer Shania Twain. 

Read also: 'Onward' review: Whimsical, fantastical journey with lots of Pixar's pixie dust

Third spot went to another new release, Sony's Bloodshot, a superhero film starring Vin Diesel. It took in an estimated $9.3 million.

Universal's thriller The Invisible Man placed fourth, at $6 million. It stars Elisabeth Moss as the former girlfriend of a man who returns to haunt her after supposedly committing suicide.

And in fifth spot was another new film, Universal's thriller The Hunt, at $5.3 million. Hilary Swank and Betty Gilpin are among the stars in a tale of a dozen strangers who find themselves being pursued, as a sport, by a group of wealthy hunters.

Rounding out the top 10 were:

Sonic the Hedgehog ($2.6 million)

The Way Back ($2.4 million)

The Call of the Wild ($2.2 million)

Emma ($1.4 million)

Bad Boys for Life ($1.1 million)