Road Block Game

import pygame
import random
pygame.init()

#General Variables
running = True
window = pygame.display.set_mode((400,600))
clock = pygame.time.Clock()

#New Variables
randx = random.randrange(0, 300)
randy = 0
score = 0

pygame.display.set_caption('Race car')

class car(pygame.sprite.Sprite):
    def __init__(self,location):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load('racecar.png').convert_alpha()
        self.x_change = 0
        self.x = 370
        self.y = 430

car1 = car([370,430])

#The Loop
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
    #key detection
    if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                car1.x_change = -5
            elif event.key == pygame.K_RIGHT:
                car1.x_change = 5
    if event.type == pygame.KEYUP:
        if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
            car1.x_change = 0
    #When roadblock gets to the bottom put back to the top & add to score
    if randy > 570:
        randy = -100
        randx = random.randrange(0, 300)
        score = score + 1
        print(score)
    #move the roadblock down
    randy = randy + 5
    #change the car position
    car1.x += car1.x_change
    window.fill((0, 0, 0))
    #draw the roadblock
    rect1 = pygame.draw.rect(window, (255, 255, 0),(randx, randy, 100, 30))
    #draw the car
    window.blit(car1.image,[car1.x,car1.y])
    #Make an invisible rectangle around the car for crash detection.
    rect2 = pygame.Rect(car1.x,car1.y,70,150)
    #Draw the screen
    pygame.display.update()
    #Check to see if the rectangles have crashed
    if rect2.colliderect(rect1):
        print('crash')
        running = False
    clock.tick(60)