Police now believe a series of knifepoint robberies in Lincoln are possibly connected.
The most recent happened Wednesday. Police say a gas station was held up around 8:30 p.m. at the Casey's General Store at 550 West Cornhusker.
Police said a masked man had a 3-4 inch knife and demanded money from the clerk and left with an unknown amount of cash.
Police are looking for a 6 foot tall black man with a lighter complexion, wearing a black t-shirt.
It's a similar description to four other robberies that happened in September and early October.
Lincoln police say 2013 has seen the number of convenient store robberies rise significantly. There have been 20 reported so far this year. By this time in 2012, only eight convenient store robberies were reported and in 2011, only four.