Global Vs local string in C

[fitcat]

Here is my program for the problem AVION1 and it got SIGSEGV when submitted in C99 strict:

#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#define MAX_LEN 10
//char line[MAX_LEN+1];
int main() {
   bool found = false;
   for (int i = 1; i <= 5; ++i) {
      char line[MAX_LEN+1];
      scanf("%s", line);
      if (strstr(line, "FBI")) {
         printf("%s%d", found ? " " : "", i);
         found = true;
      }
   }
   puts(found ? "" : "HE GOT AWAY!");
}

When I change the local var line to global, it got AC.
Please tell me why.