Editor's note: Story includes vulgarity.

Smartphone owners are once again venting on Twitter after two more overnight Amber Alerts left them confused, frightened and annoyed.

One alert was sent Friday at around 4 a.m. by officials in West Reading, Pa., about 60 miles northwest of Philadelphia, where police say two young sisters were abducted from their home.

The full alert, posted by the Pennsylvania State Police, reads as follows:

“On August 29, 2013, at approximately 9:00 p.m., Dania Perez, a 6 yr old Hispanic female, 40 inches tall, thin build with black hair and brown eyes, and Janeth Perez, an 8 yr old Hispanic female, 48 inches tall, thin build, black hair and brown eyes, were abducted from their home in West Reading, PA. They were abducted by Hostin Perez-Corza, a 23 yr old Hispanic male, 6 feet 2 inches tall, 170 pounds, black hair brown eyes. They fled the scene in a 1999 Ford Expedition, white in color, bearing PA Registration JJZ-5836.”

It wasn't the only Amber Alert of the night. At around 12:15 a.m., officials in Raleigh, N.C., sent out an alert for a 1-year-old girl last seen in a stolen vehicle.

Both alerts have since been canceled. The Pennsylvania sisters and the North Carolina toddler have both been safely recovered, according to police updates.

But just as in similar recent cases, smartphone users who received the loud alerts during the overnight hours seemed startled, bewildered or just plain agitated.

Last year, the wireless industry and the Federal Communications Commission launched the Wireless Emergency Alert program, which automatically sends emergency alerts to smartphone users with newer models. Amber Alerts were added to that program in January, and since that time, multiple alerts have been sent to users’ smartphones.

But the system seems to be testing people’s patience, particularly when alerts are sent during the late-night or early-morning hours. In July, an alert sent just before 4 a.m. in the New York City area sparked a flood of angry tweets from people startled by their beeping phones, which many said wouldn't stop beeping until they got up to turn them off.

An alert in California earlier this month prompted a similar reaction, with phone owners complaining about 10-second-long late-night buzzing noises.

Critics of the phone alerts say the late-night disruptions are going to prompt cellphone users to opt out of the program, which would mean they wouldn't continue receiving any alerts. In a Twitter rant in July, Rachel Figueroa-Levin, a columnist for amNew York, called the system a failure of public policy.

Pennsylvania Twitter Safety