LAS CRUCES, N.M. (AP) — The governor told New Mexico residents to keep attending houses of worship after small explosions outside two churches put parishioners on edge.

There were no injuries or deaths from the small blasts that occurred Sunday just 20 minutes and a few miles apart, but congregants at the Las Cruces churches were shocked.

FBI spokesman Frank Fisher said investigators will look into any possible links between the blasts and the June fatal shooting of nine black churchgoers in Charleston, South Carolina.

He said there was no immediate indication of a connection.

"That's definitely part of the investigation (but) it's too premature to make any conclusions," Fisher said.

Gov. Susana Martinez promised that the "coward" behind the blasts will be caught. If the intention was to frighten those who worship, it failed, she told reporters Sunday.

Authorities have declined to provide specifics on the explosives, but the blasts at Calvary Baptist and Holy Cross Roman Catholic had the potential to cause serious injuries if somebody had been nearby, Fisher and Las Cruces police spokesman Danny Trujillo said.

Both churches sustained minor damage. One of the blasts sent shrapnel flying.

Authorities were working to determine who planted the explosives and have not said if more than one person was being sought. Investigators also were trying to determine what materials were used and whether the blasts were related.

"It doesn't appear to be coincidental because of the timing, but you never know," Trujillo said.

The Bureau of Alcohol, Tobacco, Firearms and Explosives and New Mexico State Police are assisting the investigation.

The FBI has established a hotline, 1-800-225-5324, for information on the blasts.

"Somebody out there knows something, and we want them to call us," Fisher said. "These were strong devices."

The first explosion occurred about 8:20 a.m. in a mailbox on a wall near the administrative entrance to Calvary Baptist. Several worshippers were inside the church and services had not started.

Churchgoers said the blast shook the building and left debris around the damaged mailbox.

The next blast came from a trash can outside Holy Cross Catholic around 8:40 a.m. as Monsignor John Anderson was helping pass Communion.

"I was right in the middle of saying the words 'take and eat, this is my body,' and there was a pow! I mean, I knew it had to be more than a gunshot," Anderson told the Las Cruces Sun-News newspaper (http://bit.ly/1ME7PEp ). "I just kept on saying the words."

Ann Marie Sullivan, a college student attending Mass, said it sounded like shattering glass. The trash can was near a glass entryway, which was damaged.

Police arrived and evacuated the church and blocked off surrounding streets. Bomb-sniffing dogs searched the building.

Trujillo said he didn't know of any recent threats against either church.

Police advised officials at other churches in the city to look out for anything suspicious but not to inspect anything themselves.