Pleasanton police are investigating a bank robbery and two robbery attempts, all of which took place within a 24-hour period on May 7.

Police spent much of the morning Tuesday searching for a man who held up the Chase Bank near the intersection of Hopyard Road and Stoneridge Drive at about 9 a.m.

No weapon was seen. The suspect received an undisclosed amount of cash and fled the bank on foot, according to a police report, which said no car connected to the suspect was seen.

He is described as a black male, 35 to 40 years old, 5 feet, 10 inches to 6 feet tall, with a mustache, wearing a baby blue hat, a blue-and-white plaid shirt, baggy blue jeans and black shoes. The man was last seen on foot near the bank, a police news release said.

Two other robbery attempts the same day -- one at about 1:10 a.m. and the other, at about 10:40 p.m. that night -- may be linked, according to police.

In the first, two men with handguns approached an employee of Nations in the 5300 block of Hopyard Road, police said. The robbery was unsuccessful and the two were seen leaving the scene in an older white four door Honda.

In the second, two armed men attempted to hold up both N.Y. Pizza and Pasta and Taco Bell at the Rose Pavilion in the 4000 block of Santa Rita Road. The men pointed handguns at the employees and attempted to rob both businesses, and again were unsuccessful, according to police.

While they were in Taco Bell, one of the suspects appeared to signal to the other and the two ran out of the business without and money or property. They were last seen running on foot south through the parking lot toward Rosewood Drive. No car associated with the suspects was seen.

One of the suspects was described as a black male adult, 18 to 20 years old, 5 feet, 11 inches to 6 feet tall, weighing about 160 to 170 pounds. That suspect was wearing a black ski mask, a dark blue hooded sweatshirt with the word Hollister in white lettering across the chest, dark baggie blue jeans, and black gloves with yellow webbing between the fingers.

The second suspect is also a black male adult, 18 to 20 years old. He is 5 feet, 8 inches to 6 feet tall, again weighing 160 to 170 pounds. He was wearing black ski mask, a gray hooded sweatshirt, faded baggie blue jeans, gray gloves and had a black backpack or messenger bag.

Anyone with information that would assist in either investigation is encouraged to contact the Pleasanton Police Department at (925) 931-5100.